LOS ANGELES (AP) — The long-unsolved 1986 killing of a young Southern California woman has been linked to a convicted serial killer who admitted the crime, authorities said Tuesday.

DNA from the killing of Cathy Small, 19, matched William Suff, who was sentenced to death after being convicted in 1995 of 12 murders that occurred in Riverside County from 1989 to 1991, said Los Angeles County sheriff’s Lt. Patricia Thomas.

Suff was known as the Riverside prostitute killer or the Lake Elsinore killer, Thomas told a news conference. He was also convicted in 1974 in the death of his 2-month-old daughter in Tarrant County, Texas, and despite being sentenced to 70 years in prison he was paroled to California in 1984.

Small’s body was found on a street in South Pasadena, a small Los Angeles suburb, at 7 a.m. on Feb. 22, 1986. Clad in a nightgown, Small was found to have been stabbed and strangled.

She was a Jane Doe until a resident of Lake Elsinore, about 70 miles (110 kilometers) southeast of South Pasadena, called detectives and said that after reading a news story about the killing he was concerned that it could a local prostitute who lived with him for several months.

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The resident identified Small and told investigators that the night before she was found dead she had told him a man named Bill was picking her up and giving her $50 to drive with him to Los Angeles, Thomas said.

The case nonetheless remained unsolved for years.

In 2019, an LA county medical examiner’s investigator contacted homicide detectives after responding to the natural death of a 63-year-old man found on a couch in a South Pasadena house across the street from where Small’s body was left.

“The coroner’s investigator observed several disturbing items in the house, numerous photos of women who appeared to have been assaulted and held against their will, possibly by the decedent,” Thomas said.

In his bedroom there was a newspaper article about the identification of Small as the victim of the 1986 killing, she said.

Detectives went through the Small killing file and discovered that the evidence was never subjected to DNA testing. Subsequent testing matched Suff and another unknown man, but not the man found on the couch, who was not linked to any crimes, Thomas said.

In 2022, detectives interviewed Suff over two days at a Los Angeles County jail.

“He confessed and discussed in detail the murder of Cathy Small,” Thomas said. “He also discussed and admitted to some of the previous murders in Riverside County.”

Investigators are not expected to seek to try Suff in the Small killing because of his prior convictions and pending death sentence. There has been a moratorium on the death penalty in California since 2019.

Small had two small children and a younger sister, authorities said. Thomas read a letter from the sister, who was not able to travel to the news conference.

“My sister, Cathy Small, was not a statistic,” the letter said. “She was a protective big sister, a loving mother, and a good daughter. Kathy was funny, smart, and caring. She had a big heart and would do anything for anyone.”