Canadian police say the slain American rapist was a serial killer

A man who died in a US prison serving time for rape has also been identified as a serial killer.

The Royal Canadian Mounted Police (RCMP) said Gary Allen Srerey, who died in an Idaho prison in 2011, strangled four women in Alberta in the 1970s.

Sreri may be responsible for a string of unsolved murders and sexual assaults in western Canada, police say.

The victims were Eva Dvorak, 14, Patricia “Patsy” McQueen, 14, Melissa Rehorek, 20, and Barbara McLean, 19.

All four women lived in Calgary and disappeared between 1976 and 1977. Their deaths were investigated as suspicious or homicides at the time, but remained unsolved for nearly half a century.

“For nearly 50 years, Alberta RCMP have used all investigative tools to identify the person responsible for this tragic death,” said Superintendent David Hall at a press conference Friday.

The suspect was eventually identified through advanced DNA technology, which allowed investigators to build a family tree using data and patterns from DNA sites found on the victims' bodies.

Dvorak and McQueen disappeared in February 1976 when they were in high school while walking together in downtown Calgary. The next day, police said their bodies were found on Highway 1 west of Calgary.

Rehorek was a domestic worker who had recently moved to Calgary from Ontario for work. Police said her body was found in a ditch 22 kilometers (13.6 miles) west of Calgary in September 1976, a day after she disappeared.

Police say McClean was working at a local food bank at the time of his death, and was last seen in February 1977 walking home after a night at a bar with friends. His body was found six hours later outside of Calgary.

Superintendent Hall said if Sreri were still alive, he would be charged with murder in all four deaths.

Sreri, a U.S. citizen who was in Canada illegally at the time of the murder, fled the U.S. after facing rape charges in California, police said.

Alberta RCMP Inspector Brenne Brown said he has an “extensive criminal record for sexual offenses” in the U.S., including rape and kidnapping.

After arriving in Calgary in 1975, police said Sreri lived under several aliases and used false IDs to apply for welfare.

He later moved to the lower mainland of British Columbia, where he lived undetected by law enforcement until he was convicted of sexual assault in 1998 in New Westminster, southeast of Vancouver.

Sreri served five years in prison for this crime and was deported to the US, where he was re-arrested in Idaho and sentenced to life in prison.

According to a 2008 news article from the Idaho NBC affiliate, Sreri was accused and later convicted of raping a 44-year-old woman in Coeur d'Alene, near the Idaho-Washington border.

RCMP are asking for the public's help in piecing together Sreri's life in Canada, saying it is “particularly troubling” that he eluded police for more than 20 years, from entering the country illegally until his arrest in British Columbia.

They also offered comfort to their families. “Finding the perpetrator will not bring back Eva, Patsy, Melissa or Barbara,” Chief Hall said.

“But my sincere hope is that their families can get answers about what happened to their loved ones all those years ago.”