scott falater is a successful engineer. he's working at motorola. yarmila falater pretty much is in charge of the kids. >> it's not on. >> yes, it is. >> michael is 12. he's your typical boy. and then you have megan falater. she's 15. scott and yarmila have been happily married for over 20 years, and scott calls her yarm for short. >> tierra bueno. that's spanish for good land. it's a residential neighborhood, middle class. northeast phoenix at that time had reputation to be a very safe, quiet community. >> we don't usually respond there. it's not a high-crime area you normally work. >> my name's michael falater. my father is scott falater. in 1997, i was 12 years old. my father was hard at work. he was a product engineer for motorola. religion was always important in my family. we were members of the church of jesus christ of latter day saints. he was teaching early morning seminary. so he would wake up and he'd be teaching the seminary at 6:15. he'd drive my sister to school. and then he would drive to work. and he'd usually be home for dinner. jan

prosecutor, juan martinez, seized on a remark made in the notes of a psychologist who had interviewed scott falatern jail. a phrase scott used during their conv"unfgiest it? do. >> jnhe bigstthis, that somehow yarmila had committed some kind of a horrible something, suggesting unfaithfulness by yarmila. he kept grinding on that for motive. >> when you say unforgivable sin, it suggests she had cheated on scott falater, but that's really not the case, is it? >> i'm not suggesting anybody committed the sin of adultery. i can't get into mr. falater's head and look to see what he considered to be an unforgivable sin. it is his phrase. >> so when you uttered the word unforgivable sin, what did you mean? >> i felt that perhaps i had committed the unforgivable sin by killing yarm. >> during the six-week trial, the jury heard testimony from 52 witnesses. 180 court exhibits were marked and put into evidence. but it took only eight hours of deliberations before the jurors sent word to the judge they had a verdict. >> we, the jury, duly impanelled and sworn in the above-entitled action, upon our oaths do find

yes, i spoke with scott falater about what happened that night and to his son who still hopes his fatherna prison. the world outside his cell may have changed but the father of two says one thing stayed the same. he maintains he has no memory of committing an unthinkable act. have your thoughts changed at all about what you believe happened that night? >> i cannot swear on a stack of bibles that i was sleepwalking. all i can say is i do not know what happened. >> reporter: falater is serving a life sentence behind bars after what began as a typical evening back in 1997 turned tragic. a story he first told former "20/20" correspondent connie chung back in 1999. >> then the kids went to bed at 9:00. my wife was asleep on the couch with "e.r." on television. i kissed her good night and went up to bed myself. >> reporter: but less than an hour later, a neighbor would watch in horror as the former preschool teacher, yarmil yarmila falater is murdered at the hands of her husband. >> what is your emergency? >> her husband you threw i believe the wife in the water. >> reporter: police arrive at