Legere was convicted in the murder of shopkeeper John Glendenning, of Black River Bridge, New Brunswick, which occurred on the evening of June 21, 1986. After cutting the power, Legere and his accomplices Todd Matchett and Scott Curtis, broke into the elderly couple's store. After repeatedly beating John and his wife Mary, the trio fled the scene. Mary regained consciousness and discovered her husband had been beaten to death; she crawled up the stairs to the phone and dialed 911. The dispatcher spoke with Mary on the phone until the emergency forces arrived. Police tracked down the three and arrested them. Matchett pleaded guilty to murdering John Glendenning and brutally beating his wife Mary; Curtis and Legere were convicted at trial.
Legere was serving his murder sentence at the Atlantic Institution maximum security penitentiary in Renous-Quarryville, under the responsibility of the Correctional Service of Canada (CSC). On May 3, 1989, Legere was transported by CSC personnel from the penitentiary to the Dr. Georges-L.-Dumont Regional Hospital in Moncton, New Brunswick, for the treatment of an ear infection. Legere managed to convince the CSC personnel to let him use a washroom at the hospital alone, and there he picked the lock on his handcuffs with a homemade key he had hidden in a cigar. He then used a piece of television antenna that he had concealed on his body as a weapon, and held the officers at bay before fleeing the building. Legere escaped the hospital property and through a combination of carjacking and motor vehicle theft, was able to evade recapture.
Legere was at large for a period of seven months and during this time committed four additional murders in and around the towns of Chatham, Newcastle, and adjoining communities (now part of the city of Miramichi). The individuals he murdered were Annie Flam (May 29, 1989; during this incident, Flam's sister was also assaulted); sisters Linda and Donna Daughney (October 13, 1989; Legere set fire to the Daughney home before leaving), and Father James Smith (November 16, 1989). Legere was recaptured on November 24, 1989, following a failed carjacking that began in Saint John and ended outside Rogersville; rewards of $50,000 were collected for the information that led to his arrest.
In August 1990, Legere was convicted on charges pertaining to his escape, and sentenced to an additional nine years. His trial for the murders began with an indictment in November of that year. Legere's trial featured the first Canadian uses of DNA profiling to convict rather than exonerate; in November 1991, Legere was convicted of the murders committed while he had been at large.