PORTLAND, Ore. (KOIN) — A suspected serial killer will soon be hauled back to Clark County and charged with the murder of a teen found dead in the 1970s.

Warren Forrest has been behind bars since 1978, serving a life sentence for his conviction in the 1974 murder of Krista Kay Blake.

But he’s suspected of abducting and killing a total of seven women and girls on both sides of the Columbia River. One of those girls was Martha Morrison.

Prosecutors in Clark County recently issued a first-degree murder warrant against Forrest for Morrison’s killing.

Detectives believe Forrest’s first victim was Jamie Rochelle Grissim.She disappeared after going to school in 1971 and has never been found; however, her school ID turned up along remote Doe Valley Road in Clark County.

Hunters found the bodies of Carol Valenzuela and Morrison nearby in 1974.

In an unexpected discovery revealed in 2017, Morrison’s DNA was found on a dart gun that Forrest admitted to using to attack another woman.

An undated photo of Martha Morrison. (Clark County Cold Case Unit, July 13, 2015)

Also in 2017, Forrest was busy trying — and failing — to convince the parole board he’s no longer prone to violence from extreme stress.

“The distraction was deviant fantasies and my crime was living out one of those fantasies,” he said at the time.

Forrest has never admitted to other killings or if he knows where Grissim’s body is hidden. But Grissim’s sister Starr Lara hopes he can now be convinced to reveal what happened to Grissim while being prosecuted for Morrison’s murder.

“Now they have some weaponry for plea bargaining that they didn’t have before,” Lara said. “That would be incredible if maybe they could say, ‘Hey, tell us the truth about Jamie and the other girls, what happened.'”

Lara knows Forrest holds the key “to give the families truth.”

“He’s the only one who can do it,” she said.

Forrest is expected to be transferred from the state penitentiary in Walla Walla to appear in Clark County court sometime next week.

“It’s a long time coming,” said Lara. “So it’s really good news.”