Reporter: Atlantic City legendary for its slots, signature shows, and of course this moment. ??? Miss America ??? Reporter: But the boom and bust of the casino industry has made America's favorite playound a hotbed for crime, corruption and a startling number of unsolved cases. Cases like April Kauffman's but Kim pack and her dogged attorneys Patrick and Andrew Darcy drilled downetermined to get answers. Behind the scenes Kim with us was nonstop digging. Digging for answers, getting proof, we were on an island, all on our own. Reporter: But the tide may be turning. I grew up on the beaches and the boardwalk of Atlantic City and I ways had sand in my shoes. Reporter: Meet Damon Tyner, son of one of Atlantic City's fabled firefighters and a longtime cop. Your dad was a bit of a legend? Yeah, he was, was very well known throughout the comnity. Reporter: But the younger Tyner made a name for himself as a superior court judge. Good to see you. How you makingut? So they named a pizza for me. I think righthere? Yep, that wld be me. Reporter: And then last year. Became the first black prosecutor in the county's history. So help me god. Reporter: Many seeing him as the city's much needed savior. You're doing a great job man. Great job. I appreciate it. Thanks a lot. Thank you. How are you doing, you alright? Not judge anymore. Good to see you. That man is cleaning up A.C. There you go. You took a pledge when you took the office. Tell me about the pledge. Dating back to 1970, there are about 140 unsolved homicides and I urged my executive staff to tell me which cases were most solvable. Unanimously they all came back to me and said the murder of April kauffm. Reporter: But Tyner is sworn in almost five years after April Kauffman's murder, five long years. A lot of people wondered why five years passed and no recognizable work, had been done. It wasn't that there were glaring mistakes, it was just an omission of effort, you might say. Reporter: We wondered about that and tried asking former prosecutor Jim Mcclain about the instigation. His spokesperson tells "20/20" that Mcclain has no comment. Fortunately Damon Tyner became procutor and his team, came to the conclusion that this case should be prosecuted. Reporter: Patrick for the first time, someone's, someone's listening here. Tyner agreed to meet Kim pack and her lawyers within that rst month. What did that mean to you? The fact that I was lucky enough for him to say "I'm going to take a second look at this." Me? My case? Thank you. Like this is all I've been asng for this entire time is for someone to care. Reporter: It took three hours for Kim's lawyers to unpack all they had uncovered. You should take a look at these records. Reporter: But no evidence as compelling or illuminating as this. Today's July the 11, 2014. Reporter: A four and a half hour long video deposition of Dr Jim Kauffman himself finally talking for that wrongful death lawsuit Kim has filed. Bauically I ask the questions you give the answers, understood? Yes. They now have this incredibly valuable piece of evidence four and a half hours under oath is a lot of time. It's a lot of questions. I do. Reporter: There he is in the hot seat for the very first time getting grilled on everything from his love of guns. How many guns do you own? Approximately8. Reporter: To the moment he first saw his wife lying lifeless on the floor. I ran upstairs, I looked inside and unfortunately saw April lying there and she wasn't moving and she had a palor which I've known after 30 years is obviously someone is passed away and I ran downstairs and went out on the lawand was hysterical and started vomiting. Do you have any tissues by the way? I got them. Do you need a break? No. When I look at a deposition, I sometimes turn the sound down. I don't want to hear what they're saying. I want to see what they look like, and what their Fial expressions are. He struck me as a manipulative guy. Reporter: But there's a barrel-sized bombshell about to drop. The doctor's casual and stunning admission about a secrete's been keeping for years. Seems that time he spent the special forces weren't so special. Have you ever served in any branch of the military? No. Reporter: That's right. Dr kffman's forced to come clean about his so-called stellar litary record. Those purple hearts? Those sharpshooter medals? All lies. Did you ever tell Kim pack you were in the military? Yes. Id you ever -- did she ever do a project for college and part of the project was you being in the military? Yes. And wt you went through? Yes. And that you carried bodies? Yes. And the torture you had gone through? Yes. Did you ever tell anyone you were a green beret? Yes. Who did you tell? I don't recall how many people I told. So he created this background that didn't even really exist. That is correct. Once you start examining someone who is bold enough to engage in stolen valor, you start realizing that there are other aspects to this man's life that would require us to investigate. Reporter: But in that deposition Kauffman posits his own theoes about who may have killed his wife. Who do you think did it? I thoht it could be someone who was one of the veterans. Reporter: The last choice was that it was someone in a motorcycle gang. What motorcycle gang? The pagans. Reporter: The pagan motorcycle gang? Remember April had a penchant fomotorcycles could that mean she was in deep with the kind of people known for violent behavior? The pagan outlaws are the equivalent of the hell's angels. They are felons of the most dangerous sort. Reporter: Coming up a stunning turn in the Kauffman case. I'm going to kill myself. Reporte leading to a standoff in the garden state. Drop the gun.