A man RCMP believe is responsible for the 1974 slaying of a teen in B.C. has also been linked to four homicides in the U.S.

RCMP have scheduled a news conference in Surrey, B.C., Tuesday as part of the ongoing investigation into the disappearances or killings of at least 18 young women in B.C.’s Interior since 1969 — cases that have come to be known as the Highway of Tears slayings.

Bobby Jack Fowler was arrested in Newport, Ore., in 1995. (Lincoln County, Ore.)

CBC News has learned that police will announce that DNA has linked American convict Bobby Jack Fowler, now deceased, to the killing of Colleen MacMillen, 16.

Fowler, who died in prison in 2006, is also a suspect in four other unsolved homicides of female teenagers in Lincoln County, Ore., in the 1980s and 1990s, the county’s district attorney said in a release late Monday.

Two were slain in a double homicide in 1992 and two others in a separate double homicide in 1995.

Fowler was not a suspect at the time of his 1996 conviction in Lincoln County for kidnapping, assault and attempted rape. But in 2009, authorities reopened the cold case files and began working with RCMP earlier this year while investigating Fowler.

Missing and murdered Gloria Moody. Murdered. Williams Lake. 1969 Micheline Pare: Murdered. Hudson Hope. 1970 Gale Weys. Murdered. Clearwater. 1973 Pamela Darlington. Murdered. Kamloops. 1973 Monica Ignas. Murdered. Terrace. 1974 Colleen MacMillen. Homicide. 100 Mile House. 1974 Monica Jack. Murdered. Merritt. 1978 Maureen Mosie. Murdered. Kamloops. 1981 Shelly-Ann Bascu. Missing. Hinton, Alta. 1983 Alberta Williams. Murdered. Prince Rupert. 1989 Delphine Nikal. Missing. Smithers. 1990 Ramona Wilson. Murdered. Smithers. 1994 Roxanne Thiara. Murdered. Burns Lake. 1994 Alishia Germaine. Murdered. Prince George. 1994 Lana Derrick. Missing. Terrace. 1995 Nicole Hoar. Missing. Prince George. 2002 Tamara Chipman. Missing. Prince Rupert. 2005 Aielah Saric Auger. Murdered. Prince George. 2006 (Source RCMP Project E-PANA)

The RCMP said in a release earlier Monday that they would announce "a significant development" in their ongoing efforts to solve the cases of at least 18 women missing or killed in the B.C. interior.

Police revealed no further details, but did say families that might be affected by the announcement have been notified that the information is going to be made public.

"Police will also be issuing a plea for assistance from British Columbians, Canadians and Americans," the release said, adding that "a representative from the United States" is also going to speak at the news conference.

It’s the first time that police have mentioned any possible U.S. connection to the northern B.C. missing women cases.

Tuesday’s news conference is to be followed by two additional news conferences in Kamloops and Prince George on Wednesday, RCMP said.

Highway of Tears slayings

The RCMP unit that is conducting Tuesday's news conference is known as Project E-PANA, the unit that is investigating the Highway of Tears slayings.

The Highway of Tears originally referred to a number of deaths and disappearances along a 700-kilometre stretch of Highway 16, a remote mountain highway between Prince George and Prince Rupert.

The Project E-PANA investigation has since been expanded to include a number of other deaths of women on other B.C. Interior highways, including highways 5 and 97.

MacMillen was last seen hitchhiking along Highway 97 near Lac La Hache, B.C., south of Prince George, on her way to see friends.

Police say they do not believe a single killer is responsible for all the deaths and disappearances, and they have some strong persons of interest in three or four cases, while others remain complete mysteries.

Other groups put the number of women missing or killed along the B.C. Interior routes as high as 43. Most were members of First Nation communities.