PORTLAND — More than 30 years after her daughter’s death, Candee Wilson has confirmation of what she had always known.

“I knew literally from the day she died that it was the I-5 Killer,” said the mother of Julie Reitz, who was raped and murdered in February 1981. “The night that she left I warned her, I said: ‘Be careful, there’s a dangerous person out there.’ ”

Portland police said Thursday that advances in DNA technology allowed them to link Randall Woodfield, known as the I-5 Killer, to the deaths of the 18-year-old Reitz and two people slain in a Portland home in November 1980 — Doug Altig, 24, and Darcey Fix, 22.

Detective Jim Lawrence, with works for the bureau’s Cold Case Unit, said investigators can now “definitively prove” that Woodfield killed seven people during an early 1980s crime spree — five in Oregon and two near Redding, Calif. The I-5 Killer, who might be responsible for as many as two dozen more homicides, also committed at least 25 robberies during the crime spree, many involving sexual assaults, the detective said.

Woodfield, 61, was arrested in March 1981 and is serving a life sentence for the murder of an Oregon woman and the attempted murder of another. He won’t be prosecuted for the deaths of Altig, Fix and Reitz unless he becomes eligible for parole. Rod Underhill, the chief deputy district attorney in Multnomah County, said that is a very slim possibility.

The death penalty is not an option because it was not allowed in Oregon at the time of the crimes, Underhill said.

Woodfield, a wide receiver drafted by the Green Bay Packers in 1974, has not confessed to the murders, said Sgt. Paul Weatheroy, who interviewed Woodfield at length in 2005, when DNA linked him to the 1980 killing of Cherie Ayers of Portland.