(SINISTER MUSIC) Someone must know what has happened to Do Trieu. People just don't disappear. We are determined to resolve this for the family of Do Trieu. 68-year-old grandfather Do Trieu was reported missing from his Wellington home in 2008. With missing person investigations, most people are generally located or are found and are cleared from our missing person files. (UNSETTLING MUSIC) But some are never found. Of the more than 400 on the official missing persons list, police suspect at least 35 have been the victim of foul play. (SPEAKS VIETNAMESE) TRANSLATOR: I call him on a Wednesday, and nobody answered. He didn't pick up the next day either. (UNSETTLING MUSIC) It is the ultimate, sort of, mystery ` about what's happened to this person. Police believe it's never too late to solve a cold case, but your help is imperative. We've brought a specialist team together to review some of New Zealand's most haunting unsolved cases. They'll use their skills and expertise to look at things with fresh eyes. I think with finding the body will give us... the answers to this investigation. My family and I feel like we let my grandpa down because we couldn't find his body. I gave them my assurance that we'd do our utmost to investigate and find out what actually happened to Do Trieu. (SPEAKS VIETNAMESE) TRANSLATOR: My dad's wish when he die was to be buried with the ancestors in Vietnam. Being an investigator is all about getting those answers for people ` the resolution, the closure that they need to move on with their lives. Yeah, a lot of things come up from the frustration. Yeah, it continues to... bother me about what's happened to him. 10 years later, a much-loved father and grandfather is still missing, and his family still don't have any answers. Can you help us solve the mysterious disappearance of Do Trieu? ('COLD CASE' THEME) Captions by Maeve Kelly. Edited by Antony Vlug. www.able.co.nz Captions were made with the support of NZ On Air. Copyright Able 2018 (UNSETTLING MUSIC) Retired taxi driver Do Trieu disappeared from his Wellington home on or soon after August the 20th 2008. His body has never been found. He simply vanished. He had travelled with his wife and, uh, a group of friends... to Rotorua for a small holiday. And, uh, they had all returned together to Wellington on the 20th of August 2008. This was the last confirmed sighting that anybody had of him. Do ` a husband, father, and grandfather ` was reported missing by his daughter Hanh more than three weeks after he was last seen. (SPEAKS VIETNAMESE) TRANSLATOR: He was supposed to take me for a driving test. When I called, no one answered. That's when I knew he hadn't come back. Do Trieu was a, uh, Vietnamese refugee who had grown up and lived in Vietnam for most of his life. Came to New Zealand in the middle of his life after, I guess, a... pretty tumultuous sort of existence in Vietnam ` going through a war, imprisonment, a refugee camp ` and then he's made a good go of his life in New Zealand. He had a family,... and he was described as an honest, hardworking man. I think it's incredibly sad. He's left behind a number of grandchildren, a number of children... and the opportunity to go through to his twilight years. He was very gentle, and he was full of laughter, and he's very educated,... and, yes, he wanted the best for me. I think there's cases in New Zealand ` they're very, very rare ` where people can just... literally disappear off the face of the Earth. (DRAMATIC MUSIC) (SPEAKS VIETNAMESE) TRANSLATOR: The last time I saw my dad was on a Saturday. We took him to a restaurant for yum cha, and that was the last time I saw him or spoke to him. (OMINOUS MUSIC) When my grandpa went missing, my mum was very confused, frustrated and then angry, because nobody called her regarding to my grandpa's trip, and then suddenly he gone missing. Not knowing if her father had returned from Rotorua, Hanh alerted police. Three weeks had passed, which put police on the back foot. They began with investigating the apartment of Do Trieu and his wife, Chi Nguyen. It put us behind the eight ball by three weeks. Uh, an investigator spoke to a number of people, including family members ` uh,... Do Trieu's wife, who was residing in Rolleston St at the time. Yeah, it was difficult. The family ` and, obviously, the wife, Chi Nguyen ` didn't have the best grasp or understanding of English. Um,... obviously, Vietnamese was the principal language spoken. Chi told Police Do had gone to Auckland with a friend for business the day after they returned from their Rotorua holiday. Look, I think it's entirely, um, plausible that Do has left Wellington. We can't discount that there were people in the Vietnamese community in Auckland that Do did know. Um, however, there were no indications at all from our enquiries that he had actually travelled to Auckland at all. What we'd established back in 2008 was that we didn't have his body; he hadn't used his cell phone; he hadn't used his bank cards. When we receive a missing person's report, we were provided with some basic information about who they are; where they were last seen; the circumstances of their disappearance; whether it's unusual, out of character... Pieces of information that give us... an early understanding about what we're dealing with. With no body and no immediate explanation for the disappearance, Police considered the options. One of the things that we looked at was some form of misadventure. Do Trieu had` his passion was fishing. However, uh, scene examination of his vehicle located all his fishing gear. He wasn't out fishing when he died. If he had, uh, befallen some accident, we would expect to find his body. And we would expect to find his body because he didn't travel too far off the beaten track. He wasn't an outdoors person; he didn't go off in his vehicle by himself. On that basis, we think that if he had had some form of misadventure, he had to have been found by now. The investigation team in 2008 also considered the possibility of suicide. He was financially OK. He had a loving family here. He had a great network. He was independent. Yes, he had his health issues, but they were being managed with medication. He never indicated to any family member or any friend that he was, uh, sad or depressed in any way. Absolutely nothing has come out to suggest that Do may have wanted to` to take his own life. A police scene examination of his Rolleston St home found no signs of a struggle or any suspicious forensic information. However, five years after Do's disappearance, police relooked at the missing person case and had an overwhelming feeling that things didn't add up. Yeah, after a review in 2013, um, the matter was prioritised, as we saw some risk in the investigation, and a team was thrown into the investigation. We quickly came to the finding that, uh, we believed Do Trieu had been killed by a person or people within our community. Five years after a former Wellington taxi driver went missing, police have launched a homicide investigation into his death. 69-year-old Do Trieu was last seen alive in 2008. I met with the family of Do Trieu. I believe that the family knew that, uh,... their father was dead and that he was potentially the victim of foul play. Um,... I was just confirming to them what I believed that they knew as well. This investigation, for me, is just the` I guess, the pinnacle of investigations. It's a man who's disappeared, essentially, off the face of the Earth, uh, with no trace, no body found. Our aim is, obviously, to recover the body and find Do Trieu so we can get him back to his family and give them, uh,... the opportunity to bury him and give him the funeral that he deserves. I guess for every police officer there will be certain enquiries or events that they've seen or worked on that'll travel with them forever. For myself, this investigation is one that I will carry with me. What made police believe they were now dealing with a murder? Where is Do Trieu's body, and who was responsible for his death? Can a new investigation, a murder investigation, answer these questions? (THEME MUSIC SWELLS) (FENCE RATTLES) In 2008, Vietnamese refugee and grandfather Do Trieu disappeared from Wellington after returning from a road trip. It was originally treated as a missing person's case, but five years later, police launched a murder investigation. We've brought together a group of specialist detectives to review key information and search for clues to solve this cold case. Leading our investigation will be Detective Senior Sergeant Warwick McKee, one of the first officers to suspect Do had been the victim of foul play. With the investigation being updated to a homicide, we quickly identified that cell phones, uh, electrical data, bank information becomes very crucial. Working alongside Warwick from the beginning is Detective Senior Sergeant Martin Todd. We don't know what's happened to him, and that's, uh,... it's` it is a real mystery. And as a detective, it's those sorts of mysteries that you really... uh, wanna solve, especially for the family. ...and Detective John Harlen, who is plagued by the unsolved case. It's certainly something that I think on daily. It bugs me that we, uh, haven't been able to answer satisfactorily about what's happened. We` We have some theories; we've got some thoughts; we've got some evidence that takes us certain places, but we have nothing concrete. The specialist team come together to take a look at what's been discovered since the launch of the murder investigation. We will also be looking to you, the viewer, to help solve this homicide. OK. Martin and John, I've asked you to come in this morning so we can re-familiarise ourselves with Operation Dustin, the homicide investigation regards to the death of Do Trieu. (DRAMATIC MUSIC) The first thing the specialist team consider is whether or not Do and his wife, Chi, actually returned to Wellington from their holiday with friends. Their trip to Rotorua became really crucial ` critical ` to the enquiry, because the most important thing you really need to work out is that last known sighting, when we can account for their whereabouts. Cos that gives us a starting point as to where they were, what their frame of mind was, who they were talking to ` um, all those little clues that will give us a good indication of, perhaps, what's happened. To confirm the last sighting of Do, the team look to his electronic footprint and track his cell phone's polling data. What that polling data relates to` as at the time that that call or text message began or was sent, it tells us what cell tower the communication transmitted by. So up here, we see this is Kapiti Island, and this is travelling down State Highway 1 along the coast here, towards Wellington. This is essentially the last known sighting of Do in terms of an electronic footprint that he's made, in terms of use of his phone. Polling data, it's not definitive in what it tells us. It doesn't tell us exactly where the person was. It does give us a general geographical idea about where that phone was at that time. Again, it doesn't tell us who had the phone, but it does tell us where the phone was. And that data is irrefutable. That data doesn't lie, does it? It's an electronic footprint, as you say. So, certainly, we rely on that information that they provide us as being accurate. The electronic data backs up Do's friend Duc's statement, who said Do and Chi returned to the capital. Certainly, the fact that, uh` that Do's car was at his Rolleston St car park was certainly corroborated... Duc's interview statement that he made that Do and Chi left his place in his car. Yeah, I'm, um,... I'm very comfortable that he's, uh, got back to Rolleston St on the 20th of August 2008. Keeping in mind the phone data, the team relook at the initial statement given by Do's wife, Chi. She, uh, talked about coming back to Wellington. The next day, Chi was out, and she got a phone call from Do. And in this phone call, he says to her that, uh, he's taking off to Auckland with a friend. And Chi wasn't too concerned about this because, prior to this, a couple of months earlier, he'd talked about wanting to go and live in Auckland. (SPEAKS VIETNAMESE) TRANSLATOR: When I call his mobile, he didn't pick up. Whether it be CCTV, cell phones, computer access ` all those things leave a digital footprint. With the right tools and access to information, we can recover a lot of that and actually find out what people have been doing. Um, she said the next time she heard from Do was the following day, and, uh, she says that was the last time she heard from Do. After about a week, started getting concerned. Did you see Do in Wellington or on the way to Auckland on the 21st of August 2008? When police looked closer at the cell phone data from both Do and Chi's mobiles, it raised questions about the Auckland trip. Sort of, one of the things that first leapt out to me is that there was no phone activity, uh, at all, on the 21st or 22nd of August. The Vodafone data contradicts Chi's statements. It was concerning to me because we had no record of those phone calls at all. There was nothing to lead us to believe that Do had ever travelled to Auckland. Do's cell phone never polled again, ever. The potential that he's used someone else's phone, a friend's phone... Mm. Mm. ...that he was with, I think that's negated as well, because Chi says that he called her number,... um, and, again, there's no records of any other` Hmm. Mm. ...number calling Chi at the time that she discusses. And I was able to go through every phone call that she received over that period and identify every person who made that call. Uh, in essence, that told us that Do had not been in contact with Chi on those days. So the fact that his phone never polled again anywhere in New Zealand... suggests that` to us that he never left Wellington after, uh, the 20th of August. So what happened to Do in 2008? Do you, the viewer, have any information? Why did Chi say Do called her on that day and again on the 22nd of August? The detectives need to understand more about Do and Chi and their relationship. (THEME MUSIC SWELLS) You can do better. Sorry? Get approval before you buy with a secured gem car loan rate at just 9.99% fixed per annum. So you can get the money faster when you find the car you want. You can do better with gem powered by Latitude. Apply today. (UNSETTLING MUSIC) The Cold Case detectives are investigating the mysterious disappearance of Vietnamese grandfather Do Trieu. Originally a missing person enquiry, detectives are now convinced they're dealing with something far more sinister. Do's wife, Chi, told police her husband had phoned her from Auckland the day after the last confirmed sighting of him. However, phone data shows no calls were made from Do's phone and no calls were received from Do on Chi's phone. With this information, the team begin to unravel a complex web of relationships involving the couple. In one interview, I spoke to one of Do's very good friends, and he explained to me that, uh` that they had met online. And he actually told me that he didn't want Do to bring Chi out to New Zealand. He felt that there were perhaps some cultural differences. Do had been in New Zealand 28 years, and... she was coming from a village in Vietnam with no exposure to Western culture. And he was concerned that Do's expectation was essentially that he wanted her to come out and help, uh, look after him. Yeah, end of 2007, she arrived in New Zealand, and... a couple weeks later, they got married. (SPEAKS VIETNAMESE) TRANSLATOR: I first met Chi when they came back from Vietnam. I didn't know that he was knocking at the door, and when I opened the door, Chi was with him. This is a fairly fast-moving relationship. Uh, you talked about the age difference as well. What sort of age gap was there between Do Trieu and Chi Nguyen? So it's, um, 28 years' difference, so, um,... uh, what I'd call significant. (SPEAKS VIETNAMESE) TRANSLATOR: I didn't like her, because she was a lot younger than me. Men always, um, looking for younger. That is our culture. When we receive a wedding invitation, the very first, and common, question that we will ask the` the groom ` that is, 'How old is she?' And then they will be very much proud and say that, 'Oh, she's much younger than me.' And because that is like a key of success, and the proudness of`of men, who have` who has a younger woman. Uh, she was a carer, effectively, for him ` um, doing all his cooking and cleaning. Yeah, I think it was an opportunity for Chi Nguyen to, uh, expose herself to, uh, New Zealand culture and New Zealand life. Um, but as part of that, she probably had to succumb to... what he wanted and his demands, while she was here in New Zealand. So, looking at Do's history ` which was really important to the enquiry, to find out who he is ` we see that he has been involved with a number of women, uh, over the course of his lifetime. And the general theme that came out of those relationships was that he would often, uh, make endeavours or enquiries to find a new partner prior to ending his previous relationship. Chi was Do's fourth wife. When Do first arrived in New Zealand in 1980, he brought his second wife, Phuong. They had two children. While he was still married to Phuong, he travelled to Vietnam and brought back Cam, who became his third wife. Cam was, uh, very taken by Do ` found him to be an honest and, uh, sincere man. She felt that he loved her, and she, uh, definitely had fallen, uh, head over heels in love with him. And they shared a lot of good times. (UPBEAT DANCE MUSIC) (SPEAKS VIETNAMESE) TRANSLATOR: He showed me how to dance, but I always step on his feet, which made him laugh a lot. But I got much better, and he boasted to his friend that I didn't step on his feet any more. But two years later, Cam was given an ultimatum. Do presented her with some divorce papers out of the blue, which, um, totally shocked her, and she was devastated. (SPEAKS VIETNAMESE) TRANSLATOR: I felt hurt. He had told me he loved me. When he got sick, I took care of him for month. He promised to give to me $5000 after the divorce, but he gave me nothing. (DRAMATIC MUSIC) Before the divorce, Do had already travelled to Vietnam to meet Chi. From a` a, sort of, Western European perspective, having four wives,... we may view that with some, I guess, suspicion. And I guess we have to be careful about projecting our views about that on to possible motives, uh, and reasons for his disappearance. It may be that, um, Vietnamese culture is different in terms of how relationships actually work. For men, that is, uh, common practice. Cannot find luck from the first marriage, and then they divorce, and they cut the past, and then nothing involve in the past any more. And then they move on, and then they can meet their second or the third, the fourth, the fifth, or the` even the 10th ` no problem. No problem. Is it possible that before Do went missing, he was casting around for wife five? There had been some previous phone calls and communication between Do Trieu and his daughter Hanh, where she told us that he was, uh, upset on the phone to the point where he was crying. (SPEAKS VIETNAMESE) TRANSLATOR: Before he go to Taupo, he called me. His voice was shaking, and he had a fight with Chi. He say she has a boyfriend, and that's how the fight started. I was afraid something might happen to him, so I told him to come and stay at our house. Chi Nguyen was attending an English school here in Wellington, uh, while she was residing in Rolleston St. And from, um, speaking to the, uh, English language school teacher, she, um,... believed that there was some form of relationship between Chi and another student there. We... looked into that aspect. It's unlikely that particular person is, uh` is involved. The team discovers Do had even sought legal advice. Do had gone to his family lawyer and had had a draft contracting out agreement drawn up. Contracting out agreement, I guess, is like the American prenup. Basically, if the relationship between him and Chi, um, dissolved, would protect him from losing all his hard-earned assets. How did that go down with Chi? She thought that, uh, it was unfair to her. She thought that if she left Do, it would be OK for him to retain his assets, and she was basically due nothing in the relationship. But she was certainly concerned, uh, that if he left her, that she would get nothing. And she didn't want to sign this ` sort of, the way I understood it ` on the basis that if Do left her, she would essentially be left stranded, or high and dry, in New Zealand with no real support. But at the time of his disappearance, she's never signed it. (EXCLAIMS) So, in our culture, we don't have prenuptial agreement. And even we never thought about that. And we don't have any formal agreement ` or even informal agreement ` between husband and wife. (DRAMATIC MUSIC) (SPEAKS VIETNAMESE) It's more than offence. We should be shock. 'What is it?' And it will show that is` that person... could not love the other person, could not want to have a love, don't want to be together. Now, we know that Do and Chi had perhaps reached a point where they couldn't come to an agreement about the future of their relationship. So it` Again, it's entirely plausible that Do has left New Zealand, uh, unbeknownst to Chi, with a view to meeting someone else in Vietnam, to begin a whole new relationship. The option that, potentially, Do Trieu has left New Zealand and returned to Vietnam ` how we eliminated this as an option. There's no overseas phone calls at all. There's no sign of any forward planning, um, to do that, which that` you'd expect, um, if they were going overseas. And the other thing is ` is he'd need a passport to leave New Zealand. Police determined Do only had a New Zealand passport. It's never been found, and there are no records of him using his passport after his mysterious disappearance. It was becoming a critical point for Chi, um, in terms of the forms she needed to complete to, uh, remain within New Zealand. And Do had expressed to her ` as far as we're aware ` that he had concerns about continuing with that process, which would ultimately have meant that Chi would have had to have left New Zealand. Chi would have been feeling very, very vulnerable, isolated,... um, 'What do I do with my life? 'I've` I'm here. I've been here for a year now, nearly. 'I've invested a lot of time and energy, and I` I don't wanna go back to Vietnam. I love it here.' I'm aware, from an interview with one of Do's good friends, that Chi actually reached out to him without Do's knowledge. And she expressed her concerns about the fact that, uh, Do may not continue with this relationship and cause her to return to Vietnam. So certainly, um, she was concerned and worried enough about that to reach out to one of Do's good friends without Do knowing. I guess, looking into anyone's relationship, it's often hard to know uh, what's really happening. People can be guarded and closed, and... only let certain people in to certain pieces of information. But having spoken to a wide range of people now in the investigation, I think there was a realisation for him, though, that he still had a` a large part of his life to go. And if the relationship wasn't going to work out, I guess he made a pragmatic decision, um, not to continue with the visa sponsorship process. Were there any further issues putting strain on their relationship? The team again looked at Do's electronic footprint, but this time to bank records, which apparently Chi had very little knowledge of. Well, he had his financial affairs structured so that she couldn't access his accounts. We are aware, though, from speaking to a number of people, that at one stage, in the middle of 2008, a substantial amount of money came off term deposit; and for a brief period of time that came back into an account that they shared. Ballpark figure-wise? Anywhere, sort of, between $140,000, $170,000, on term deposit at that time, which was generating a reasonable amount of interest. Chi told police Do had intentionally transferred the money into the joint account. The team have subsequently found out that the deposit into their shared account seven weeks before Do's disappearance was ultimately a bank error. We're aware that she did see that sum of money in that bank account that day. It was probably the first time she was ever aware of the existence of that sum of money, which, who knows, may have, uh, given her a number of thoughts about, um,... 'Is he hiding money from me? Am I entitled to this money?' So when it came time for the contracting out agreement, she would have had knowledge of the types of, sort of, assets that he had. (DRAMATIC MUSIC) The Cold Case detectives have unravelled a web of intrigue. Do had financial assets; he had a pattern of casting around for a new wife while still married; and the 68-year-old was considering ending his marriage to Chi, forcing her to return to Vietnam. Nearly 10 years on, can the team track Do electronically and prove he didn't leave Wellington? (THEME MUSIC SWELLS) * * (TENSE MUSIC) The Cold Case team investigating the 2008 murder of Vietnamese refugee Do Trieu has discovered he'd asked his fourth wife, Chi, to sign a prenup agreement. Thinking that if Do has gone to Auckland, as Chi claimed, then he's likely to have taken his bank cards. The detectives look to Do's bank records for clues. So, it became quite important to establish what bank cards Do had, what bank accounts he had,... and what bank accounts that she had access to. He had essentially one overriding account, and within that, he had sub accounts, where he had a joint account that he shared with Chi. Do only had one bank card, which could access all of his accounts. Whereas Chi could only access the joint account. So on the 22nd of August, we see in central Wellington ` in Cuba St, Cuba Mall ` that both Chi's card and Do's card have both been used that day. So we have two different cards being put in exactly the same location; and we also have funds being withdrawn from the joint account; and also an attempt to withdraw funds, uh, from the personal account of Do, which were unsuccessful. This indicates that the person trying to get the money was not Do, because he would have known his PIN. And this confirms the fact that it's very unlikely that Do Trieu has left Wellington and gone to Auckland. Absolutely. It's` Yeah, we would expect him, even if he had, uh, travelled to Auckland, to still retain his bank card. With the transactions in Wellington post-22nd of August, some of the retailers had CCTV footage. When we obtained that, the person captured in the footage is Chi Nguyen. You know, I guess one of the interesting things is the information that's still out there. You know, obtaining these bank receipts, these electronic records,... uh, phone records, that were still there. Cross-referencing both phone data and bank records, the Cold Case team unearths texts in Vietnamese sent from Chi's cell phone. When we received the data, we had a number of communications from Chi to an unknown number. Uh, we were able to finally identify who that person was in 2013. On the 5th of September, Chi had made a purchase at Dick Smith Electronics, here in Wellington. Yeah. We were able to go back and ask if they were able to show us, uh, what that purchase was for. I mean, that was crucial in building our picture of what's happened. On that receipt was the cell phone number that these text messages had been, uh,... sent to. Now, on that receipt was the name Thuan Nguyen. Thuan was a friend of Do's ` playing chess and fishing together. Back in 2008, when police first spoke to Chi, Thuan assisted in the enquiry. There was a language barrier there, and Chi thought that, uh, Thuan may be able to explain the situation clearly to attending police. Acting as an interpreter, as such. Yeah, an informal interpreter. And he can communicate fluently, uh, in English and Vietnamese. The team now focuses on the texts sent between Chi's phone and the phone bought at Dick Smith with Thuan's name on the receipt and has them translated. Later that evening, Chi replied to that in Vietnamese, and said, 'Thank you,... Some strong messaging for a very short relationship, isn't it? Absolutely. We have Do... going missing on` around the 21st, 22nd of August, and then, prior to him being reported missing, we have Thuan, Do's best friend, sending a text message to Chi saying, uh, that he misses her so much. It leapt out to me ` 'Is there some sort of romantic relationship 'between the two of them?' And occurring so close to his disappearance... Had they reached out to each other in a time of stress, with his disappearance ` uh, which can sometimes happen ` or was this relationship occurring, uh, prior to Do going missing? Thuan told police that he wasn't the writer of those text messages. However, he did admit to and talk about the relationship he had with Chi. When I spoke to Thuan, he certainly acknowledged to us that he had been in a romantic relationship,... uh, with Chi. A sexual relationship? He definitely admitted having, um, a sexual relationship with Chi. (SPEAKS VIETNAMESE) TRANSLATOR: Chi phoned me and asked me to take her to the immigration lawyer because Mr Do was in Auckland. I took her to the lawyer, and he asked me to write a letter of recommendation for Chi. Afterwards, she came back to my house, and we made love three times. After Mr Do had been gone for about a week, Chi phoned me again. She said she felt strange that he had been away for so long. Through talking to family and friends, the Cold Case detectives unearth further details. Before Do's even reported missing, Chi is offering to give away personal possessions of, um` of Do to Hanh. It was some of his personal property. Other people that we've spoken to, items like a computer have been, um, offered to them. This is unusual behaviour, isn't it? It is. And, um,... interesting. Yeah, within a week and a half of him disappearing, and he's, um, supposedly up in Auckland temporarily. Hanh was very concerned for` for Do, and thought it was unusual. And she had raised this with Chi. (SPEAKS VIETNAMESE) TRANSLATOR: I thought Chi might be hiding something, so I call her and say if he didn't come back, I would call the police. And she told me not to. Phone records actually show us that Hanh and Chi spoke quite regularly from the 23rd through to the 14th. They obviously had discussed at length about what was happening. By, uh, Chi not wanting to be in contact with police. It may have been that, again, she just thought it would bring unnecessary embarrassment on her and Do if the police became involved. There was certainly evidence in Do's history that he did just up ` get on a plane and disappear for large periods of time without telling people. So there goes two competing, sort of, views there. Chi saying, 'Look, he's fine. He's up in Auckland. 'Don't cause, um, unnecessary embarrassment,' and Hanh's, I guess, natural family instinct to know that something, um, wasn't right. And she ultimately took it upon herself to come and see police herself. As we've gone through the investigation, each stone we've overturned and looked at and found new information. There's certainly been moments where we've gone, 'Eureka.' Sometimes those enquiries have gone nowhere, um, and that's frustrating. But 10 years on, the Cold Case team haven't given up hope, and a new discovery involving Chi's immigration documents may unlock new secrets in the disappearance of Do Trieu. (THEME MUSIC SWELLS) * The Cold Case team has exposed a series of unusual incidents involving Chi Nguyen following the disappearance of her husband. Despite Do Trieu vanishing, she's continued with the residency visa process. To accompany her application, she provided three letters of support ` one from Thuan; one from Uyen Huynh, another friend of Do's; and Duc Tri Le, who travelled to Rotorua with Chi and Do. As part of the Cold Case investigation, police handwriting expert Delwynne Walsh examines these documents. She compares the support letters to handwriting specimens by each of the people. (SUSPENSEFUL MUSIC) So, in the case of the letter by Thuan Nguyen... Looked reasonably fluent and speedily completed. Um,... it has a very skilled handwriting style, and I compared that to the specimens I received for that writer, and I analysed all of the letter forms, etc ` all of the aspects of the handwriting, like the style, the size, the slope,... and all the things we look at. (TENSE MUSIC) So, as non-experts, you'll all see a lot of pictorial similarities straight away. We've also got the very subtle constructional features in the way that the individual letters are made. This would be a difficult signature to successfully copy or simulate without leaving evidence of that. And there was no evidence of copying or simulation, so I concluded that that letter had been written and signed by the specimen writer, um, who wrote those specimens attributed to Thuan Nguyen. For the second letter, um, in the name of Uyen Huynh ` same thing. I went through, I compared to her specimen handwriting. Again, I concluded that the author of these specimens, Uyen Huynh, had completed that second letter. (DRAMATIC MUSIC) Then I came to the Duc Tri Le letter. On the surface, pictorially, it looked similar to Duc Tri Le's handwriting. When I went through and analysed it all microscopically, there were actually a number of significant differences. (DRAMATIC MUSIC) The letter A in the questioned letter ` that was broken down and made of individual strokes, whereas Duc Tri Le makes his letter as one continuous movement and then one separate movement for the cross stroke. Duc Tri Le, his H's were done with a downward stroke and then a cross stroke leading up to the next downward stroke, whereas the H's in the questioned document were three separate strokes; and the sequence, from what I can see, appears to be different. So with Duc's letter, you believe that the handwriting on there has been copied and it's not his? I can't say who did it, but it would be very hard, I think, to copy a whole page of his handwriting in a way that looked like him, without natural habit slipping through. (DRAMATIC MUSIC) Duc confirms to detectives he never wrote the letter. On the 24th of October, police conducted a scene examination of Do and Chi's flat. They found nothing suspicious. (UNSETTLING MUSIC) A week after the search of the address in Rolleston St, Chi then visits a flight agent and books flights ` return flights ` to Vietnam. Interestingly, she paid for that ticket using, uh, the bank card belonging to Do Trieu. This is the card that detectives believe would have been with Do if he'd gone to Auckland as claimed. And the next day, she's travelled up to Auckland. Just prior to her departure, she was stopped and spoken to by police at the airport in Auckland, at Immigration, when she left. There was no reason for police to stop and, uh, prevent Chi Nguyen leaving the country at that time, because the investigation, when she departed on the 2nd of November 2008, was still a missing person's investigation. The airport police officer did a really good job there. They've actually put in their notes the numbers` Yeah. ...um, relating to the bank card that she was in possession of, which then we were able to confirm with the bank that it was the, um, bank card issued to Do Trieu for access to his accounts. The information that Chi had Do's bank card when she left New Zealand for Ho Chi Minh City, in Vietnam, is vital. There was no use of that bank card in New Zealand at all after that date that she departed? That's correct. However, it was used again. Accessing Do's bank records show that withdrawals of around $2000 each month were being made in Vietnam ` money from his pension and interest on his investment. There were a number of transactions that occurred in Vietnam, in Ho Chi Minh City with Do's card as well. And those transactions actually continued on a regular basis through the course of 2008... and also into 2011, uh, until that card was cancelled by the bank. I mean, I know that people would try to kill him for money. He's` He's an old man. He has... illnesses and heart condition, so it would be an easy target. And that's what I believe. (SPEAKS VIETNAMESE) TRANSLATOR: Chi left New Zealand without my knowledge. I found out when the police called me. I was very angry. I think Chi fled the country to escape from her guilt. It's important to get Chi to come back to New Zealand and assist us with the investigation. (VEHICLE HORNS BLARE) However, this seems unlikely. Currently, there's no extradition treaty between New Zealand and Vietnam. So the only way Chi Nguyen would come back to New Zealand is voluntarily. I'm strongly of the belief that, uh, there is someone out there who... we've spoken to, and perhaps hasn't told us... everything. I believe that Do,... he hasn't gone far from his home in Rolleston St on the 21st or 22nd of August, and I believe he's likely met his fate somewhere in this area. Where is body is now is obviously of importance to us. He's got a large family, and we owe it to them to get his body back to them. I have no doubt that people in the community will know what happened to him. They may not know that their knowledge is important to the enquiry, but they will have... certain snippets that are relevant, that can help us. So if we obtain those, we just put one or two more pieces in that puzzle, and that may take us to his body. (SOMBRE MUSIC) What I want from all of this was to` what my mum wants ` to have his... body back, so then we can give him a proper burial and then take his ashes back to our ancestors. But if we can't find his body, we would like to know how he died,... because it's still a mystery. For a number of reasons, uh, the Vietnamese New Zealand community may feel they cannot approach police. However, I am appealing to them to come forward and, uh, speak to us, uh, and we will treat you with respect ` and, uh, pass on the information that you may have that will help us to resolve and solve this matter. (SPEAKS VIETNAMESE) TRANSLATOR: I hope that anyone who knows about my dad, could they please come forward and tell the police, so they can find my dad and we can return him to Vietnam to be with his ancestors. (POIGNANT MUSIC) We put various questions to Chi Nguyen. She denies any involvement in the murder of Do Trieu and believes he is still missing in New Zealand. (UNSETTLING MUSIC) ('COLD CASE' THEME) Copyright Able 2018