Did someone drive her to murder . Or did she . She was a cunning, ruthless woman. Hello. And welcome to dateline. The story youre about to see, centers on the death of a military man thousands of miles from a battlefield. A dedicated officer who survived war zones, only to be caught in the crossfire of a lovers triangle. Heres keith morrison. What was she thinking . When she went to the computer . When she typed in those five, little words . Did she not understand where those little words might lead. Where are you at . Reporter michelle was, no doubt about it, dissatisfied. Here she was, young, successful, attractive. And it wasnt exactly boredom that was eating at michelle. She was starting a new career as a psychologist, often counseling troubled couples. I think she was newly licensed. That was her first job. Reporter she would laugh that events would propel her that newspaper reporters would be poking around in her past. Michelle, to everyone i spoke to, was trying to be somebody. She was trying to become a professional. Reporter michelle at an early age, always seemed confident in getting what she wanted. She was 16 when she started dating marty. Marty was a couple years older, worldly, bright, had big plans. He wanted to be a astronaut. He went to the air force academy. She was 20, when she married him, in the famous chapel outside of colorado springs. You may kiss your bride. Reporter this was 1991, where marty was everything she ever wanted. Long before she talked to that psychologist. Agreed to talk about the events that were about to come and the happy days with marty, too, of course. We did everything together. He treated me really well. I thought we had the perfect relationship. We were best friends. Reporter he was the dashing officer back then. She, his lovely bride. The future she imagined, an e endless honeymoon, where martys career would take them to exotic destinations around the world. She didnt imagine that world would be posts in oklahoma, and fayetteville, North Carolina. Marty was a captain by then. Flew one of those huge c130 cargo planes. All that time alone, not that easy on a marriage, that she revealed with tape recorded interviews with psychologist debbie cole. Marty was away for extended periods of time. She was having a hard time with that. She was getting lonely. Reporter sometimes he was gone for months, sometimes when he did come home, military families have gotten to know that adjustment period too well. They bickered about having children. He wanted them, she didnt. She was worried she would be stuck raising them herself, where she was lonely. Loserville. No one to hang out with. No one to pick up the phone and call. Reporter that was about the time it started. Harmless, raleally, a few key strokes. Sexy brunette seeks rendezvous man. And not long after, she got a response. From him. His name was john. John diamond. John was a ladys man. Reporter debbie could see her brother responding to a solicitation like michelles. My brother has a great personality. Haez hes an attractive guy. Reporter after meeting online, they met in person, at a restaurant. Talked about movies, music and things that marty and i didnt talk about. Reporter john diamond was an Army Staff Sergeant, trained at ft. Bragg and was highly regarded, decorated. He was a good soldier. He was a playboy himself. He left the first wife and they had a son together. Reporter michelle didnt know that john was still married. Maybe it didnt matter. At least not then. She loved the sex, the attention, the excitement. He was very attentive. He was very affectionate. He was very adoring. Yeah. It felt great. Reporter what made her so desirible to him . It was the sex. Reporter for michelle, it was more lust than love. She felt the affair did not take away from the fact she loved marty. She said he was the love of her life. Reporter and marty . He was in the dark, of course. When michelle told him their marriage was in crisis, and he wouldnt agree to see a counselor. He wouldnt see a counselor and i moved out. He was shocked. Reporter she moved in with john diamond. He would rub my feet, if i wanted him to. Reporter he never met a person like her before. She challenged him in ways he had never been challenged before. She was strong and exciting for him. Reporter was he enough for her . Apparently not because after three months on her own, michelle went back to marty. She felt like the marriage could survive. Despite everything that happened that she could make it. Reporter john and michelles sixmonth affair seemed to be off. Then, apparently, it was back on. The two traveled to the Tropical Island of saba, where michelle interviewed for a job at a university. And later that fall, a romantic rendezvous at a hotel where they would celebrate her 30th birthday. But michelle told the psychologist it was just a relapse. I knew i loved marty. I wanted to make it work in my heart. Reporter john diamond was devastated. He said, i cant live without you. You cant do this to me. Im going to drive my car off of a bridge. Reporter it was awful, michelle said. Diamond kept calling. Made a scene in front of her office, and threatened to call marty and tell him everything. A week after the romantic night in raleigh, she met john at a restaurant to end the affair, gently but for good. It would never happen again. Never, never, never. He seemed calm and very rationale. Reporter now, it was december, time for peace and joy, christmas parties. One in particular, at which the spirits slowed and the feud burned down to its explosive end. Somebody was about to die. And somebody else wasnt taking any chances on missing. Coming up it wasnt like bang, bang, bang, bang. It was bang, pause, bang, pause. Which sounds more like what . Execution . You could take it that way, yes. When dateline continues. Walgreens. 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Imagine, most of a suburban strip mall of strip clubs and a downtown which is charming, elegant even, and a scene about everything. Its an old town, fayetteville. That tower marks the spot where North Carolina ratified the federal constitution back in 1789. Im standing on what was a slave market. Sherman fought battles here in the civil war. Now its a military town and 160,000 acres back there is the armys ft. Bragg where soldiers prepare to go to war. Nestled up beside that is Pope Air Force base. Two institutions, two professional military men, one woman. And that woman, michelle theer, now found herself caught between her husband, marty, the air force captain and her former lover, Army Staff Sergeant john diamond who just wouldnt go away. I told him, i dont want to leave my husband. I never told him, i love you, i never said, i want to be with you. I mean, i think i was pretty straight up. Now with the Holiday Season at full swing and a new commitment to her marriage, michelle and marty were on the road to raleigh, for a night out. Traveling with them was another couple from her office. They had gone to this Christmas Party that she specifically asked her boss if marty could go. Reporter it was sedate by office Party Standards and ea y early, since marty had to fly early in the morning. Marty, michelle and the coworkers prepared to leave the restaurant. Then an interruption. Michelle excused herself. Made a brief phone call out of earshot of the others. Then the drive to fayetteville. One hour. They dropped the other couple at michelles office then left for home. Stopped on the way for gas. And then sitting at the gas pump, michelle told marty shed forgotten something at the office. Turning around and going back to the office to get some stuff that i needed so i could stay up and work that night. Marty, parked behind the Office Building. Michelle walked up an outside staircase, disappeared inside. Marty, waiting in the car. Apparently he got impatient, headed up the stairs to check out michelle. And thats when it happened. [ gunshots ] she found him, she said, at the bottom of that outside doorway. She could see the blood. She ran to the nearest store, called 911. Somebodys shot . Somebody shot your husband . I think so. Where are you at . Okay. Whats your name . Michelle. Reporter within minutes Fayetteville Police and paramedics arrive and find michelle cradling her husband in a pool of blood, but it was too late. Marty theer was dead. He was just 31. Because marty was an air force captain, military investigators were soon on the scene as well as police, making this a joint investigation with the fayetteville p. D. Both teams were eager to speak to the only known witness, michelle theer. Officers special investigations unit, vince castillo. She said what sounded like her three bangs of a car back firing. Reporter did she say what she did at that point . She opened the door and saw her husband laying at the bottom of the stairs. Reporter she thought she saw someone moving in the bushes, near the stairway. But she wasnt sure. Initially police were looking at perhaps a robbery of some type. Reporter detectives combed the parking lots surrounding area but found no one on this cold, dark december night. There was a man who lived behind the Office Building who heard the shots fired who later said that he said, somebodys getting murdered out there. Because of the order in which the shots were fired. They were very calculated. It wasnt like bang, bang, bang. It was bang, pause, bang, pause. A space between each of the five shots. Reporter which sounds like what . An execution . You could take it that way, yes. Reporter at the top of the stairway were a few clues. Bullet holes sprayed in the wall. Sequins from his outfit littered the landing. He was at the top of the stairs shot from down below. I think thats what made him roll down the stairs and the final shot was to the back of the left ear. Reporter the kill shot. The kill shot. Close range. Reporter they found shell casings in the parking lot. Appeared to be from a 9 millimeter handgun. But there were no fingerprints. No footprints. No useful dna. Investigators did find martys wallet. Still on him. Complete with cash and credit cards. Marty theer was not robbed. The other thing that was a very, very cold night. Not a night where a prowler would be out on the streets just looking to find someone. It made it very suspicious. Reporter investigators couldnt imagine who would want to kill such a wonderful man like captain marty theer. But of course, out on this dark parking lot they didnt know any of what you know. Not yet anyway. Assuming what youve heard so far is the real story. And as youll see, the question of what was true and what wasnt could be very tricky indeed. Michelle said shed gone back to her office because shed forgotten something. So what took so long . Coming up they found a Candy Wrapper that had been opened in the trash can. It was almost like a scene where she had gone upstairs and sat and waited for a few minutes. For what . When dateline continues. To b. Its not sexy. Or delicious. Or fun. But since you need both car and home insurance, why not bundle them with esurance and save up to 10 . Which you can spend on things you really want to buy, like. Well, i dont know what youd wanna buy because im just a guy on your tv. Esurance. Its surprisingly painless. You know reliable support when you have it, and that dependability is what we want to give our customers. At comcast, its my job to constantly monitor our network. Prevent problems, and to help provide the most Reliable Service possible. My name is tanya, i work in the Network Operations center for comcast. We are working to make things simple, easy and awesome. It was a week before christmas 2000, and fayetteville was aglow, but not everywhere with the lights of christmas. And a few hours after air force captain marty theer turned up dead in the parking lot of his wifes Office Building, the news was out and it was big. Michelle theer, now martys grieving widow, told the police she was inside her office looking for a book when she heard someone firing outside. By all accounts it was an assassination. Reporter greg buckner was a Deputy District Attorney at the time. Someone would kill marty theer, that night, no evidence of robbery, no evidence of any other thing going on here. Reporter inside michelles office, what they found seemed, well, a little odd. Maybe. Shed gone to the bathroom. The toilet had not been flushed. They found a Candy Wrapper opened and in the trash can. It was almost like a scene where shed gone upstairs and sat and waited for a few minutes because obviously to find a book wouldnt take very long. Reporter strange. Hard to know what it meant, if anything. As dawn approached, michelle was allowed to go home. And later that morning, her boss arrived. So the cops talked to him, too. During that interview it came out she was having marital problems and was having some extramarital affairs. Reporter funny. Michelle hadnt mentioned anything about that. So detectives went to her house to followup. And sure enough, michelle did admit having an affair with Staff Sergeant john diamond. Michelle also said she hadnt spoken to diamond in two days. But when pressed, she remembered trying to call him unsuccessfully just before leaving that Christmas Party. About 90 minutes before marty was murdered. Detectives decided to check their cell phone records and discovered theyve been calling each other regularly, minimum 20 times a day. Reporter now detectives paid a visit to john diamond, who freely admitted having a sexual relationship with michelle. But claimed she was just one of many ladies in his life. And as for the night of the murder, he had an alibi. He was home with his family. Watching a movie. Still, michelle must have harbored some sort of suspicion about john diamond who was now a person of interest. Not long after the murder, as she told detectives and that psychologist, she went to see diamond, conduct her own investigation. Find out what he knew about martys death. If you know anything about this, you know anybody who had anything to do with this, please tell me. I would never do anything to hurt you. I know how much you love reporter mind you, as police were soon aware, michelle had many opportunities to question her friend, john, after her husband died. Witnesses said he parked down a little side street then walked through their yards going through the back door of her house. Reporter he couldnt stay away . Going through, staying all night. Reporter not commonly the way widows grieve, spending the night with the person of interest in her husbands murder. Michelle told psychologist dr. Debbie leighton she needed support from someone, anyone. She felt more alienated from family and friends and more threatened by the police. The only person in her life that was willing to be there for her was john diamond. I knew that i was depressed. I was getting more and more depressed. I went to john for comfort. Reporter a few weeks after martys murder, michelle and john drove to florida for a long weekend. Michelle wanted to see a former professor for grief counseling, she said later. While diamond stayed with his sister, debbie. He acted as if nothing was wrong. He knows he didnt have anything to do with it. He didnt shoot him. Reporter who did kill captain marty theer . Is it possible john diamond executed his romantic rival . He may have had a motive. Police were very suspicious. But the physical evidence was, frankly, rather weak. So detectives kept digging in the arcane world of phone records. Boring, but sometimes revealing. And one telephone number in particular caught their attention. A call from diamond to one of his army buddies at ft. Bragg. So we asked them if diamond had any access to any weapons. He said that he loaned diamond his personal pistol. Reporter which just happened to be a 9 millimeter berretta pistol, the same kind of gun that killed marty theer. John diamond had actually borrowed the gun from him during the timeframe when the murder occurred, john diamond had possession of it. Reporter detectives were now convinced diamond not only had access to a gun, but maybe even the actual murder weapon. Did he still have it . Well, apparently not. Because just a short time after cops went to the home of diamonds army buddy asking about that gun, diamond made a phone call to ft. Bragg and reported that his car, which he claimed to have left in the base parking lot, had been broken into and one of the things stolen from it was a 9 millimeter handgun. When we got there the passenger door had already been opened and there was a pile of glass sitting next to the rocker panel on the passengers side. If you look on the inside, ther