Stephanie Ilene Lazarus was born in 1959 and grew up in Simi Valley, California. She attended the University of California, Los Angeles (UCLA), where she earned a degree in political science and was an active member of the women's junior varsity basketball team. During her time at UCLA, Lazarus met John Ruetten, an engineering student from San Diego. The two developed a close relationship, occasionally dating and maintaining a friendship that continued after their graduation in 1982.

In 1983, Lazarus joined the Los Angeles Police Department (LAPD), embarking on a career in law enforcement. She was known among her colleagues for her dedication and professionalism. Despite her demanding job, Lazarus maintained her connection with Ruetten. However, their relationship became complicated when Ruetten began dating Sherri Rasmussen, a nurse and director of nursing at Glendale Adventist Medical Center. The two women were aware of each other's relationships with Ruetten, leading to tension and jealousy.

On February 24, 1986, Sherri Rasmussen was found murdered in the condominium she shared with her husband, John Ruetten, in Van Nuys, Los Angeles. She had been beaten and shot three times. The initial investigation by the LAPD concluded that the murder was the result of a botched burglary, and the case eventually went cold due to a lack of leads.

In 2009, the case was reopened by LAPD detectives who re-examined the evidence using advanced DNA technology. A key piece of evidence was a bite mark found on Rasmussen's body, which had been swabbed during the initial investigation. The DNA from the bite mark was tested and matched to Stephanie Lazarus. Further investigation revealed that Lazarus had continued to express romantic interest in Ruetten even after his marriage to Rasmussen.

On June 5, 2009, Lazarus was arrested and charged with the murder of Sherri Rasmussen. The trial began in early 2012, during which the prosecution presented evidence of Lazarus's jealousy and her prior confrontations with Rasmussen. The defense argued that the case was circumstantial and lacked direct evidence linking Lazarus to the crime scene.

After deliberation, the jury found Stephanie Lazarus guilty of first-degree murder in March 2012. She was sentenced to 27 years to life in prison and is currently serving her sentence at the California Institution for Women in Chino.

In May 2024, the California Board of Parole Hearings revoked plans to release Lazarus on parole after hearing emotional testimony from family and friends of the victim.