Shortly after she sat down at her desk on the third floor of LAPD headquarters Friday morning, Det. Stephanie Lazarus was told a suspect in the basement jail had information on one of her cases. The 25-year police veteran went quickly downstairs.

As Lazarus removed her firearm to pass through security, she unknowingly walked into a trap. There was no suspect — only questions about a terrible secret police believe she has been harboring for more than two decades.

Now disarmed, Lazarus, 49, was confronted by homicide detectives and arrested on suspicion of the 1986 slaying of a woman who had married Lazarus’ ex-boyfriend. The dramatic break in the decades-old case sent shock waves through the tight-knit LAPD community, marking one of the few times in the department’s history that one of its own officers has been accused of murder.

“It’s painful,” LAPD Chief William J. Bratton said. “But murder is also very painful.”

Calling it an apparent “crime of passion,” Deputy Chief Charlie Beck said Lazarus allegedly beat and fatally shot Sherri Rae Rasmussen, a 29-year-old hospital nursing director, two years after joining the department.

Three months after they were married, Rasmussen’s husband returned to their Van Nuys condominium on the evening of Feb. 24, 1986, to discover his wife’s badly beaten body on the floor in the living room. She had been shot several times, Beck said.

Days after the slaying, two men robbed another woman in the area at gunpoint. Homicide detectives suspected that the pair had also killed Rasmussen when she came upon them burglarizing her home, according to news reports from the time. Rasmussen’s parents, newspapers reported, offered a $10,000 reward for the men’s capture.

The search for the men led nowhere. Like thousands of other homicides from the period, the case remained open and collected dust on storage shelves as detectives struggled to keep pace with L.A.’s dramatic surge in violent crimes.

But with homicides in the city falling to historic lows, LAPD detectives have had unusual freedom in recent months to revisit cold cases. Detectives returned to the Rasmussen killing in February, testing blood or saliva samples from the crime scene and thought to have been from the killer. The DNA tests showed that the attacker was a woman, disproving the theory that Rasmussen had been killed by a man.

Detectives scoured the original case file for mention of any women who could have been overlooked during the investigation. Beck said they found a reference to Lazarus, who was known at the time to have had a romantic relationship with the victim’s husband, John Ruetten. Ruetten allegedly broke off the relationship and soon after became involved with Rasmussen, said sources familiar with the investigation who were not authorized to speak publicly.

With suspicion falling on an LAPD cop, the case took on sensitive and explosive tones inside the department. To minimize the chances that word of the reopened investigation would leak, only a small circle of detectives and high-ranking officials were made aware of it. Last week, an undercover officer surreptitiously trailed Lazarus as she did errands, waiting until she discarded a plastic utensil or other object with her saliva on it, police sources said.

The DNA in her saliva was compared with the DNA evidence collected from the murder scene. The genetic code in the samples matched conclusively, police said.

Lazarus was not pursued as a suspect at the time of Rasmussen’s slaying, according to Beck. The two homicide detectives originally assigned to the case have retired and had not yet been contacted by police, he added. Beck declined to say why the detectives did not look more closely at Lazarus as a possible suspect.

Asked at an afternoon news conference whether Lazarus had been either deliberately or mistakenly overlooked because she was a cop, Beck said: “I don’t know the answer to that at this point.” Reached at his home in Arizona, Rasmussen’s father, Nels E. Rasmussen Jr., indicated that he believes so. “We are not surprised that the arrest was made,” he said.

One of the original detectives in the case, Lyle Mayer, said he never interviewed Lazarus in the course of his investigation and continued to believe the burglary theory until his retirement in 1991.

Police officials declined to comment on whether they believe anyone else was involved in the killing. Lazarus was being held without bail and could not be reached for comment.

Officers responded with shock as news of the arrest spread through the department.

“Never in my wildest imagination would I ever think she could do something like this,” said one longtime officer, who socialized frequently with Lazarus. “We drank beers. She was always quick to give you a hug or tell a joke.” The officer spoke on condition of anonymity. Lazarus’ current partner, Det. Don Hrycyk, refused to comment.

Lazarus joined the department in 1983, a year after she graduated from UCLA with a degree in sociology, LAPD and university records show. After several years as a rank-and-file patrol officer, she was promoted to detective and, in 2006, landed a high-profile assignment with Hrycyk tracking stolen artwork and forgeries. There are references in department publications to Lazarus earning public commendation for her work.

She hardly shunned the spotlight. In a recent LA Weekly profile, Lazarus joked that all she knew about art was that it “hangs on the wall” and that “after working here and seeing all the phony art, I said, ‘I can do that.’ ” Lazarus, who according to police has a young daughter and recently married another LAPD detective, told the newspaper that she had started taking oil-painting classes and had first become interested in art when she visited Europe as a teenager. Last year, she gave interviews after helping capture two men convicted of a string of art thefts in the Wilshire area and in Beverly Hills.

Until her death, Rasmussen was director of critical-care nursing at Glendale Adventist Medical Center. Her slaying stunned colleagues, who referred to her as a vital member of the staff, according to news reports. On the day she was killed, she had reportedly stayed home from work after straining her back in an aerobics class. In an article about the family’s reward, her father said Rasmussen had entered college at 16 and had taught for a period at UCLA.

“It’s safe to say we have some closure,” said Ruetten, the victim’s husband, when reached at his home in San Diego. “It’s been a horrible thing to go through it all again.”

andrew.blankstein@latimes.com

Article by LA Times