. >> her uncle, clarence elkins, was the victim's son-in-law. he lived about an hour's drive away and had no criminal record and no history of violence. his wife, melinda, couldn't believe that clarence would kill her mother. >> i remember my reaction distinctly when he told me that my mom had been murdered. i mean, i actually doubled over in pain, you know, like in a fetal position almost. >> clarence denied any involvement but was quickly taken into custody. >> and i said to them, yes, i am his wife. and yes, i know that some women do stand up for their man and lie for them. but you're missing the biggest point here. that was my mother. and i want the person who did this to pay. and i'm telling you right now, it was not clarence. >> but police discovered that clarence might have had a motive to hurt judy johnson. >> their theory is that clarence is -- has evolved a hatred for his mother-in-law because the mother-in-law was allegedly interfering in his marriage to melinda. >> there was a woman who said she was judy's best friend, saying she was

. >> without melinda's efforts, let's face it, clarence elkins would still be in prison. >>> up next, a college coed is left for dead in a lovers' lane. >> the blood is consistent with her being struck up to ten types. >> there were plenty of suspects, but very few answers. >> these samples could have originated from 20% of the population. >> was it a random murder or jealousy? >> if he couldn't have her, nobody else could. >> for decades, the case went unsolved until now. >> he is a cold-blooded killer. >> they wanted to solve this. >> at the end of a long day in may of 1984, a farmer in tennessee made a startling discovery. >> he noticed some clothing lying in the field. there was actually a body lying there. >> the victim was a young girl wearing only a bra. her body was covered with two pairs of jeans and a dark jacket. one pair of jeans was hers, the other was a pair of men's jeans. >> also there's a black jacket across her body with a sleeve tied around her neck and a pair of panties that she was clutching in her right hand. >> she was identified as 18-year-old laura salmon, a l