Based on interviews with friends and acquaintances and recent posts to what appears to be his Facebook page, the 24-year-old Bourque was a gun enthusiast with an anti-authoritarian mindset.
"He's always seemed to have a problem with authority," Caitlin Isaac, who worked with Bourque at Wal-Mart several years ago, told Business Insider, adding that he had issues "with parents, bosses, police."
She said that Bourque was eventually fired from that job.
"I never took him seriously, but he always said he wanted to go out with a bang and bring people with him," she said.
Based on posts on the Facebook page, Bourque not only promoted the use of guns, but held libertarian views and showed hostility toward police and authority in general.
He posted a number of poems and lyrics, such as "Sharpened claws poisoned tip manicure./ Painted skin hiding the beast within./ Daggered heels designed to cut your face./ No remorse crushing the human race."
He also shared images with slogans such as "Free Men Do Not Ask Permission to Bear Arms" and "Militia Is Only a Bad Word if You're a Tyrant."
Friend 'weirded out' by recent encounter
Ann Seamans, the mayor of the small town of Riverview, which is located just south of Moncton, confirmed to CBC News that Bourque once attended Riverview High School.
Mike Campbell, who has known Bourque since they were toddlers and lives down the street from his family, told Business Insider about a recent encounter when Bourque stopped by to offer condolences for the death of Campbell's father.
As Bourque was leaving, Campbell said he made a curious comment: "'You take care, Mike. You have a good life.'"
When Campbell said they should keep in touch, Bourque responded, "'That probably won't be able to happen.'"
"I was kind of weirded out by it," says Campbell.
CBC has learned that Bourque was close friends with two employees of World's End Warehouse, a gun and weapons shop in Moncton's Riverview suburb, where he grew up.
Dave Ford, who owns World's End Warehouse, told CBC News he has never met Bourque and, to his understanding, never sold him any weapons.
But Ford acknowledged that two of his employees, Nate and Adam Plewes, were friends of Bourque's, and were away from work today given the unfolding manhunt.
'There should have been flags going off somewhere'
Campbell told Business Insider that Bourque had been raised in a religious Christian household and had been homeschooled. Campbell said that more recently, Bourque was living in a trailer park.
A person who knows Bourque from the trailer park and asked to remain anonymous told the CBC's Dave Seglins that Bourque was working full time and lived alone in a two-bedroom modular trailer that he moved into last fall.
The person said Bourque was "very affable, polite. Never had a complaint or a problem. That's why this is totally out of left field."
After seeing Bourque's anti-police posts on Facebook, the person said, "There should have been flags going off somewhere."
Asked whether she could have predicted that Bourque might ever carry out a killing spree, his former Wal-Mart colleague Isaac said she was "surprised, and also not."
She recounted a camping trip a while back with Bourque and some of their Wal-Mart colleagues at the time, in which he brought a gun.
"He held onto [it] the whole night while drinking. That kind of freaked us out, so we didn't invite him the next time."