Parole documents show that Rehn, 34, had a long history of assaults, weapons convictions, break-ins and drug use that stretched back to his teenage years in the mid 1990s.
Rehn was found dead in a home not far from the scene of the shooting Saturday.
"You are a dangerous person who has demonstrated blatant disregard toward the criminal justice system as well as lack of respect to the public in general," the Parole Board of Canada said when it denied Shawn Rehn day parole in 2006.
"Your crimes are continuous and increasing in seriousness and often resulted in serious psychological, emotional and financial harm to victims."
Six years later, before Rehn left jail on statutory release on different charges, the board said that his "reintegration potential is assessed as low."
He was rearrested in July 2013 with a fellow parolee who had convictions for armed robbery. Police searched Rehn's car and found a crack pipe, pellet pistol and knives.
Story continues after the slideshow:
The parole board rebuked Rehn for ignoring bans on having firearms.
"When you are in possession of weapons, the public is at serious risk of harm from you, as your past offending demonstrates," wrote the board the following September.
RCMP Commissioner Bob Paulson remarked on Rehn's criminal history, particularly a series of overlapping firearms bans. Paulson said it may provoke an examination of the police and justice system that allowed Rehn to be free.
"I've been policing for 30 years and I've never seen anything the likes of this,'' Paulson said on the weekend.
When four Mounties were gunned down by a cop-hating criminal in Mayerthorpe, Alta., in 2005, the Alberta Crown did a formal review of the shooter's prosecution history to determine if anything could have been done better.
That review found that while James Roszko had been charged with more than 40 crimes and been flagged as a potential dangerous offender, he did not meet the standard for indefinite detention.
A spokesperson with Alberta's Justice Department declined comment on the Rehn case Monday.
The former pipefitter and oilsands worker's criminal record, made public Monday by Alberta Justice, details a lengthy list of 57 convictions, starting in April 1999 when he was ordered jailed for two months for theft and break and enter.
In the years that followed, when Rehn wasn't serving time, he was racking up convictions in Edmonton, Calgary and the smaller communities of Evansburg and Drumheller.
They were for assault, assault with a weapon, drug possession and possession of prohibited firearms. He obstructed a peace officer, escaped lawful custody and drove while disqualified.
He also was convicted for breaking and entering, theft and possession of stolen property.
Parole Board Of Canada documents show Rehn served two federal jail terms as an adult.
The first was a two-year sentence for possession of stolen property and driving while disqualified. The second was for three years on charges including escaping custody and possession of a loaded prohibited weapon.
Collectively, he was sentenced to serve more than 12 years in custody, but it's not clear how much of that time he actually spent behind bars.
On the day he died, he was still facing 30 charges for four separate offences, including fraud, resisting a peace officer, escaping lawful custody, possessing a prohibited firearm, failing to appear in court, failing to stop for police, dangerous driving and multiple charges of breaching bail conditions.
A look at the adult criminal history of Shawn Maxwell Rehn, the man who gunned down two Mounties in Alberta on Saturday.
April 1, 1999: Convicted of break and enter and theft in Edmonton. Sentenced to 60 days jail and one year probation. Ordered to pay $921 in restitution.
April 9, 2001: Convicted of dangerous operation of a motor vehicle in Evansburg, Alta. Sentenced to six months in jail and three years probation.
Aug. 8, 2001: Convicted of assault in Evansburg. Fined $200.
May 14, 2001: Convicted of possession of property under $5,000 obtained by crime, theft, obstruction of a peace officer and breach of conditions in Calgary. Sentenced to 60 days in jail on the first charge; five months in jail on the second charge; 15 days in jail on the remaining two charges.
June 21, 2001: Convicted of failing to attend court in Edmonton. Sentenced to 45 days in jail.
Dec. 15, 2001: Convicted of assault with a weapon and two counts of careless use of a firearm in Edmonton. Sentenced to one day in jail after spending seven months in pretrial custody and a 10 year firearms prohibition.
March 4, 2003: Convicted of operating a motor vehicle while disqualified. Fined $400.
Aug. 4, 2004: Convicted of driving while disqualified in Edmonton. Sentenced to 60 days in jail.
April 13, 2005: Convicted of possession of property obtained by crime over $5,000 in Calgary. Sentenced to one day in jail.
March 3, 2006: Convicted of 16 counts of possession of property obtained by crime under $5,000 in Calgary. Sentenced to two years in jail.
March 27, 2006: Convicted of possession of property obtained by crime over $5,000 and driving while disqualified in Edmonton. Sentenced to five months in jail and given an 18 month driving prohibition.
Nov. 8, 2007: Convicted of theft under $5,000 in Calgary. Sentenced to one day in jail.
Aug. 14, 2009: Convicted of failing to comply with recognizance in Edmonton. Fined $200.
Oct. 26, 2010: Convicted of possession of a restricted firearm and possession of a prohibited firearm plus refusing to provide a breath sample, escaping lawful custody, possession of a controlled substance, 10 counts of possession of stolen property under $5,000, possession of a stolen credit card and breach of recognizance in Edmonton. Sentenced to three years in jail and five years in jail on the remaining charges, minus credit for time served before trial.
June 6, 2011: Convicted of break, enter and theft in Edmonton. Sentenced to two years in jail.
Aug. 19, 2011: Convicted of unauthorized possession of a prohibited or restricted weapon, possession of property obtained by crime under $5,000 and two counts of breach of recognizance in Drumheller, Alta. Sentenced to three months in jail.
Aug. 7, 2013: Convicted of assault in Drumheller. Sentenced to one day in jail.
Charges Rehn was facing when he died:
Oct. 11, 2013: Charged with fraud over $5,000 and two counts of breach of recognizance in Edmonton.
Dec. 14, 2013: Charged with three counts of breach of recognizance, resisting a peace officer, possession of stolen property, possession of controlled substance, use of imitation firearm in Fort Saskatchewan, Alta.
Sept. 3, 2014: Charged with possession of a prohibited/restricted weapon, possession of a prohibited firearm, escaping lawful custody, possession of stolen property under $5,000, possession of controlled substance, possession of break-in instruments and two counts of breach of recognizance in Edmonton.
Oct. 28, 2014: Charged with failing to stop for police, dangerous driving, four counts of breach of recognizance, disqualified driving, driving without insurance, and displaying unauthorized plates in Edmonton.
Nov. 12, 2014: Charged with failing to appear in court in Edmonton.
Nov. 28, 2014: Charged with failing to appear in court in Edmonton.