NORTH SYDNEY, Nova Scotia – Even those who loved and helped raise Stephen Marshall say they can only guess at what transformed the soft-spoken dishwasher from Cape Breton into the man police believe gunned down two convicted sex offenders in Maine before taking his own life on a bus in Boston.

His stepfather, Keith Miles, says the family remains in a state of disbelief amid reports Marshall used Maine’s online sex offender registry to track down the two victims, both of whom were shot Sunday in their homes.

Miles said the answer may be found in the place where Marshall, 20, was born and spent most of his adolescence: the United States.

“A lot of his teenage years were spent down there, so how would we know if anything would happen to Stephen that would trigger this?” Miles said Tuesday in an interview from his home in nearby Bras d’Or.

“We have no information on that. We don’t know every moment of his history.”

Investigators in Canada and the United States still don’t know what link, if any, Marshall had with the two victims.

Marshall, who lived for the past year in the Cape Breton community of North Sydney, traveled by bus Thursday to his father’s home in Houlton, Maine, where police say he took Ralph Marshall’s handgun and Toyota pickup.

By Sunday, he was being pursued by police as the prime suspect in the slaying of Joseph L. Gray, 57, of Milo, Maine, and William Elliott, 24, of Corinth, Maine.

When Marshall was later approached by police on a crowded bus in Boston, he pulled a .45-caliber handgun and shot himself in the head. He died later in hospital.

Keith Miles and Marshall’s mother, Margaret Miles, had been expecting Marshall for Easter dinner.

“The family was…wondering where Stephen was,” said Miles. “We were expecting him for dinner and had no idea he was in the United States.”

Instead, police called to say the young man, who had never had received so much as a traffic ticket, was wanted in a double-murder case.

“We’re devastated by this and it just seems totally out of character for him to have done something like this,” said Miles. “He was a very passive person. People seem to get surprised by that – it happens sometimes to people who are quiet…I just don’t know.”

Marshall’s father, Ralph Marshall, has said his son didn’t appear troubled and never said he had been sexually abused.

Friends and co-workers described Stephen Marshall as quiet, low-key, responsible and hardworking.

“Nothing is a problem with him. He got along with everybody,” said Donnie McDermid, who rented the youth an apartment in a weather-beaten home in North Sydney.

His co-workers at the Canton Chinese restaurant in North Sydney, where he washed dishes on the day shift for minimum wage, offered similar descriptions.

The assistant manager, Charlie McArthur, could only recall one detail which, in hindsight, might be relevant: the youth’s passion for computers.

The normally shy Marshall didn’t hesitate to tell McArthur that he loved surfing the Internet.

“He told me he used to spend a lot of time on the computer, particularly eBay, and that was the only outside interest I knew of,” McArthur recalled.

He also told his boss he was born in the United States, but moved around.

After his birth in Dallas, he and his mother – originally from Nova Scotia – and his American father came to live in Cape Breton, where the family split up.

Marshall lived in the North Sydney area until he was 13. He then left for Idaho to live with his father.

“He lived in the United States with his father for a considerable time, and his father… doesn’t seem to know what happened either,” said Miles.

Marshall returned to North Sydney more than a year ago and found part-time work.

In Bras d’Or, shock was mixed with sympathy among some residents.

“It’s a very sad story,” said Theresa Romeo, who remembers seeing the youth on occasion. “You almost have this feeling that he’s doing a little bit right, but it’s not right. I feel so sorry for him and the family.”