"I did not commit this crime," Marc Exter Jernigan told Judge Herbert Exarhos. "Hopefully the truth will come out."Jernigan, 44, was convicted of first-degree murder in the Aug. 8, 1986, slaying of June George."It's hard to be in the same room with a killer," Ronald Kasperson, the victim's son, told the defendant. "What happened to us ... you did it, in the most horrible, nightmarish way possible."Witnesses testified that George disapproved of Jernigan, who was dating her then-18-year-old daughter, Kathie Keller Dalby.Dalby said she and Jernigan were boyfriend and girlfriend in high school and broke up about two weeks before her mother was killed.Dalby found her mother's body in the kitchen of her home in the 8800 block of Mariposa Street. The victim had been stabbed 78 times.At the time, Dalby described Jernigan as "All-American" and "perfect" and said she could not imagine him killing her mother, Deputy District Attorney Jill Schall said.Dalby expressed a different view in court Tuesday."I don't need Marc, and neither does society," she said. "I fear Marc. Anyone should."Jernigan was arrested in February 2006, after La Mesa police reopened the case and tests matched his DNA to blood found on a bathroom towel at the crime scene, according to the prosecutor.The defendant's blood was also found on a bedspread and a plastic photograph holder from George's wallet, the prosecutor said.Defense attorney Christopher Plourd told the jury that Jernigan's DNA was found in the victim's home because he was over there having sex with the victim's daughter all the time.Plourd said there were problems with the evidence, alleging DNA samples were contaminated and mixed up.