A former Los Angeles police detective was found guilty Thursday of the 26-year-old murder of the wife of her former lover in a case that hinged on a single piece of evidence -- DNA from a bite mark on the victim's arm.

The first-degree murder conviction came after a three-week trial that included testimony from a forensic expert who said the DNA was a match to defendant Stephanie Lazarus.

Her defense attorney countered that the DNA was packaged improperly and deteriorated while stored in a coroner's freezer for two decades. He also suggested there might have been evidence tampering.

Lazarus could face 27 years to life in prison with the possibility of parole when she is sentenced for the murder and a gun enhancement imposed by the jury.

The case was submitted to jurors on Tuesday after intense closing arguments by both sides.

Victim Sherri Rasmussen was bludgeoned and shot to death in 1986 in the condo she shared with her husband of three months.

Detectives initially believed two robbers who had attacked another woman in the area were to blame. But two decades later, a cold case team using DNA analysis concluded the killer was a woman and authorities began looking at Lazarus as a suspect.

During the trial, prosecutors focused on the relationship of Lazarus and John Ruetten, who became her lover after they graduated from college.

He testified that he never intended to marry Lazarus, although they were intimate for about a year. He also said she enticed him into having sex with her shortly before his wedding.

"Here's the deal," he testified. "It was clear she was very upset that I was getting married and moving on."

Lazarus' lawyer, Mark Overland, ridiculed the claim of a fatal attraction between Lazarus and Ruetten, saying she never tried to reunite with her former lover after his wife was gone,

"So this obsessing with John must have fizzled out I guess," he said.

Lazarus went on to marry another policeman and adopt a daughter. She rose in the ranks of the Los Angeles Police Department, becoming a detective in charge of art forgeries and thefts.

Overland also pointed to the lack of physical evidence against her. No blood, fingerprints, hair or fibers connected her to the scene.

But prosecutor Shannon Presby told jurors the case was based on more than just DNA. At the outset of the trial, he said it featured "a bite, a bullet, a gun barrel and a broken heart."

Lazarus' gun was never found, but Presby called experts to testify that bullets fired into Rasmussen's body matched those issued to police officers in 1986.

Lazarus' husband attended most of the trial along with other family members. Ruetten sat across the courtroom with Rasmussen's family.

The deathly pale defendant and her white-haired former boyfriend never looked at each other.

But their past moved before them on a movie screen as both sides showed pictures of them as a young couple.

Among the trial's most dramatic moments came when Ruetten testified tearfully about finding his wife slain. He said it never entered his mind that Lazarus might be responsible.