Sinclair was the youngest of four children from a working class family in Jal, a small oil and gas town in the southeastern corner of New Mexico. The real J.C. Weir was a former classmate at Jal High School.
His father died when Sinclair was young, townspeople remember, and his mother supported the family by running a coin laundry and taking in ironing. "He was an average student, not particularly different from anyone else," John Cooper, one of his former teachers recalled.
A longtime coin buff, Sinclair started a coin shop during the 1970s in Hobbs, 40 miles north of Jal, using his own collection as a base.
He did well, locals recalled, and then branched out to selling guns. He renamed his shop the Shooter's Supply and catered to people who could afford $800 to $1,000 hunting rifles, collectible guns and even automatic weapons.
Sinclair was apparently well-liked, widely remembered as a friendly, outgoing man who " could talk to anybody." He and his wife, daughter Pam and son Michael enjoyed competitive shooting, one friend said, "as a family thing." Sinclair often hunted with several law enforcement officers who were among his customers.
But one day in 1985, Sinclair's shop burned. He was investigated for arson, according to Hobbs police, but was not charged. Soon after, he defaulted on a bank loan, officials said, and when the lender moved to reclaim guns put up as collateral, Sinclair left town with his family.
New Mexico then accused his wife, in absentia, of embezzlement for failing to turn over more than $30,000 in hunting and fishing license fees sold through the store.
The way Sinclair left Hobbs surprised local residents, but not the fact that he did. One close friend who did not want to be identified said "he told me he wanted to set back on his heels for a few years, that he had enough of six-day work weeks. He said he had enough money saved to buy a place with some acreage, get some mules and some horses. That maybe he'd get into real estate."
By the time police caught up to Sinclair in Kenny Lake, "he had no visible means of support," said Alaska State Trooper Sgt. Charles Grutzmacher.
The family had been living on the second floor of a rented wood-frame house with no bathroom, and an outside privy.
After Sinclair's arrest, his wife Debbie was extradited back to New Mexico, where she pleaded not guilty to the embezzlement charges and was released on bail. She told authorities she never questioned her husband about his activities or source of income, and authorities say she and Sinclair's children are not suspects in the murders.
The family, especially the children, have been "devastated," one friend reported. When they talk about their father, he said, they wistfully recall a different man who "made a real effort to teach them about animals, taught them a lot about themselves, about being independent and self-sufficient."
Many in Hobbs who remember Sinclair say they are shocked to learn that Sinclair could have been a killer. "It's like a puzzle but you can't see the picture because half the pieces are missing," one friend said.
When he died, Sinclair left behind more questions than answers. Police hoped he would talk to them, but he did not. Then he suddenly died, alone in his cell, of "heart failure," according to a preliminary autopsy.
"I'm disappointed," said Finnegan, who hoped to see Sinclair prosecuted for shooting and robbing him. "I feel cheated."
"I'm not convinced we know everything this guy did," Billings Sgt. Archer said. "We may never find out."
"For me this all but closes my case," Piccini said. "Have you ever been on a train, rolling down a track, feeling everything was great, when you go across a trestle and the track just stops? That's the only way to describe how I feel. What's left to do but go back the way you came?"