Murder Defendant in 24-Year-Old Cold Case Sentenced for Triple Homicide

San Diego County District Attorney Summer Stephan announced today that a 47-year-old man who shot and killed three people, including a 22-month-old baby, on Labor Day in 2000, has been sentenced to three terms of life in prison without the possibility of parole plus 75 years to life.

In September 2000, Sergio Contreras opened fire into an apartment, after one of the residents failed to pay for a small amount of illegal drugs. Contreras shot 27-year-old Michael Plummer more than a dozen times. He also shot 18-year-old Adah Pearson in the heart as she lay sleeping on the couch. Another shot went through the wall and hit 22-month-old Julio Rangel, Jr. in the head as he lay asleep on a bed in the next room. All three victims died from their wounds. Contreras fled and case went cold for several years.

Contreras was initially a suspect in the crime, but it wasn’t until 2007, after additional witnesses came forward, that murder charges were filed. On March 22, 2023, Contreras was successfully extradited from Mexico where he had been serving time for an unrelated robbery and murder.

“When a murder is unsolved for decades, it takes an enormous toll on the victim’s loved ones, but now the families of Michael Plummer, Adah Pearson and Julio Rangel Jr. have a measure of justice after many years of mourning their loss,” DA Stephan said. “I am grateful to our Cold Case Unit and detectives in the San Diego Police Department who worked tirelessly on this case until it was solved, and the killer was brought to justice.”

Deputy District Attorney Chris Lindberg prosecuted this case.

Established in 2003, the DA’s Cold Case Homicide Unit works with law enforcement to solve and prosecute unsolved murders. The victims come from all walks of life and from all areas of the county, including children and the elderly. The District Attorney’s Office prioritizes these cases through the Cold Case Unit, which has dedicated and experienced investigators and prosecutors who use the latest forensic technology to deliver justice to victims.

The oldest case solved and prosecuted by the unit is the 1969 rape and murder of Mary Scott which resulted in a conviction following a trial in 2022. The Cold Case Unit also manages the Cold Homicide and Research Genealogy Effort (CHARGE.) Funded by a three-year grant from the U.S. Department of Justice, CHARGE uses the power of investigative genetic genealogy to solve more cold case homicides. The San Diego District Attorney’s Office was one of only 10 prosecutor’s offices nationwide to receive this grant.