Stephanie Lazarus, 52, was found guilty in March of killing Sherri Rasmussen, a nurse who was bludgeoned and shot to death in the condo she shared with her husband of three months, John Ruetten.
Rasmussen's mother, sister and widower spoke during the sentencing hearing about their pain and described the victim as a warm, caring and loving person.
Ruetten told the judge he still grieves.
"The fact that Sherri's death occurred because she met and married me, brings me to my knees," he said. "I do not know ... how to cope with this appalling fact."
Superior Court Judge Robert Perry gave Lazarus a term of 25 years to life for first-degree murder and an additional two years for personal use of a firearm. He said Lazarus would be credited with 1,000 days for good behavior and time already served.
Her defense attorney said an appeal has been filed.
Outside court, Lazarus' brother and mother said their hearts go out to Rasmussen's family, but they still support Lazarus and believe she did not get a fair trial.
"There was never a presumption of innocence," said Steve Lazarus. "The media got to listen to DNA and guilt for 2 1/2 years before Stephanie had her trial."
During the trial, prosecutors focused on the romantic relationship between Lazarus and Ruetten after they graduated from college. They claim Lazarus was consumed with jealousy when Ruetten decided to marry Rasmussen.
The case hinged on DNA from a bite mark prosecutors say was left by Lazarus on Rasmussen's arm.
Defense attorneys argued the DNA evidence was corrupted over the years and could not be considered reliable.
Lazarus was not a suspect in 1986 because detectives then believed two robbers who had attacked another woman in the area were to blame for Rasmussen's death. The case file, however, did mention Lazarus because of her relationship with Ruetten.
No suspects were found and the case went cold until May 2009, when undercover officers followed Lazarus and obtained a sample of her saliva to compare with DNA left at the original crime scene, police Chief Charlie Beck said at the time.
Prosecutors suggested Lazarus knew to avoid leaving other evidence such as fingerprints. The idea that saliva from a bite mark could be her undoing was inconceivable in 1986 when DNA wasn't used as a forensic tool.
Prosecutors asked the judge for the maximum sentence.
"Her efforts to mislead the initial homicide investigators permitted her to avoid justice for this crime for more than 20 years," prosecutors wrote in court documents. "It is bleakly ironic that the defendant's long-running deception now benefits her with respect to sentencing."
Defense attorney Mark Overland had pointed out, however, that his client's personnel file is replete with commendations throughout her 26-year career and did not contain a single allegation of improper conduct or excessive force.
Overland added there was no evidence presented at trial that showed Lazarus knew where Ruetten and Rasmussen lived or that she knew their phone number.
"How Ms. Lazarus could have known that Ms. Rasmussen decided on the morning (of the killing) not to go to work and stay home has never been explained," Overland wrote in court documents. "Additionally, after the killing, Ms. Lazarus never initiated any contact with Ruetten."
Lazarus rose in the ranks of the Los Angeles Police Department, becoming a detective in charge of art forgeries and thefts. Her husband attended most of the trial, along with other family members.
The Rasmussen family has filed a wrongful-death lawsuit against the LAPD and the city of Los Angeles.