An American sex offender, who died more than a decade ago in prison, killed four women and girls in Calgary in the 1970s 鈥� and there may be more victims, RCMP announced Friday.

Gary Allen Srery was serving a life sentence for sexual assault when he died of natural causes in an Idaho prison in 2011.

Mounties said he already had an extensive criminal record in the United States when he crossed illegally into Canada in the mid-1970s.

The bodies of Eva Dvorak and Patsy McQueen, both 14, were found on a road beneath an overpass west of Calgary in February 1976.

Later that spring, 20-year-old Melissa Rehorek was found dead in a ditch off a gravel road outside the city.

The following year, the body of 19-year Barbara MacLean was discovered outside what was then Calgary鈥檚 city limits.

A break in the four homicides came when police began comparing DNA of the killer with profiles on ancestry websites, which eventually lead them to a match with Srery.

鈥淎t the end of the day, whether there鈥檚 a charge or no charge, we鈥檙e not fixing anything,鈥� RCMP Supt. Dave Hall told a news conference when asked about the victims鈥� families learning the killer had been found.

鈥淔or police, it鈥檚 a solution. For families, it鈥檚 just an answer.鈥�

RCMP said little is known about Srery鈥檚 life or whereabouts from the time he skipped bail in the U.S in the mid-1970s up until he was arrested and convicted of sexual assault and confinement in New Westminster, B.C., in the 1990s.

He worked jobs as a cook and a salesman, police said. He often changed his appearance, vehicles and names.

鈥淲e will still continue to build that timeline and try to understand where he was, because that may help us look at other unsolved files, whether it鈥檚 in Alberta, British Columbia or frankly some place that we鈥檙e unaware of at this stage,鈥� Hall said.

Eva and Patsy were both students at Ian Bazalgette Junior High School. They left the school together on Feb. 12, 1976, and remained together for the next couple of days, visiting the homes of various friends.

On Feb. 15, 1976, their bodies were found on the road. They were fully clothed, although police believe they had been sexually assaulted.

No causes of death were determined, said RCMP, and DNA technology wasn鈥檛 yet available.

That spring, Rehorek moved to Calgary from Windsor, Ont.

Police said she was living at the YWCA while working as a hotel housekeeper. She was last seen on Sept. 15, 1976, when she told people that she planned to hitchhike out of the city on her days off. A transit driver remembered dropping her off on the Trans-Canada Highway.

Her body was found the next day, and there was evidence of a struggle.

Police said long, black hairs found in her hand were believed to be from her killer. An autopsy determined she had been strangled.

MacLean, who had moved to Calgary from Nova Scotia, worked at a bank. She had gone to a bar with friends and was last seen walking alone about 2 a.m. on Feb. 26, 1977.

Her body was found later that morning. She had also been strangled. There was evidence of a struggle, and her jacket was on inside-out.

During their investigation of MacLean鈥檚 killing, police said more than 600 men provided hair samples and hundreds of taxi drivers were interviewed. A witness claimed to have seen MacLean getting into a cab.

Investigators kept hitting dead ends.

鈥淭he initial investigations lasted into the 1980s. And in the 1990s, no less than four task forces were created to re-examine evidence, tips from the public and any lead not previously followed,鈥� Hall said.

The homicides would finally be solved with DNA.

The killer鈥檚 DNA was compared to genetic profiles, including those on ancestry websites. Investigators found people they believed were related to the killer, and those relatives agreed to co-operate with the investigation.

Last year, police matched the genetic profile to a DNA sample on file for Srery.

Srery, born in Oak Park, Ill., in 1942, moved with his family to California in the mid-1950s. He married and had children and was divorced in 1969.

During the 1960s, he was convicted of rapes and kidnappings. At one point, he was classified as a 鈥渕entally disordered sex offender鈥� and ordered to serve his sentence in mental health custody.

In 1974, while out of bail awaiting trial on a rape charge in Los Angeles, he failed to show up for court, and an arrest warrant was issued.

He wasn鈥檛 seen or heard from again until he was arrested in B.C.

In 2003, after serving time in Canada, he was deported back to the U.S. and convicted of rape in Coeur d鈥橝lene, Idaho.

Police are asking anyone with tips or information related to Srery鈥檚 whereabouts to contact the Alberta RCMP historical crime unit.

Rob Drinkwater, The Canadian Press