The ISIS sympathizer suspected of plotting an attack in southern Ontario died from a gunshot wound during a confrontation with RCMP, provincial police said in releasing the results of the autopsy.

Aaron Driver, 24, was killed in Strathroy on Aug. 10 after the RCMP learned he might have been planning a terrorist attack. Police swarmed the home where Driver was staying, saw him leave and get in a taxi. Officers surrounded the cab and Driver detonated an explosive device moments before he was shot and killed.

It was previously unclear whether he died from injuries caused by the explosion or from a police bullet.

Wayne Driver, Aaron Driver's father, said he doesn't blame the RCMP for his son's death. (Trevor Wilson/CBC) The RCMP told Driver's family that officers had to shoot him because he had a second explosive device that he was threatening to detonate inside the cab. The taxi driver had managed to get out of the vehicle before the first explosive went off.

Wayne Driver, father of the dead man, said he's still in shock and that it has been an emotional time for the family.

He said the RCMP told him the autopsy showed several bullets struck his son, piercing vital organs. He said he doesn't, however, blame the Mounties for his son's death. In its release issued Tuesday, the Ontario Provincial Police didn't say how many bullets struck Driver.

"I'm sure they gave him every opportunity to surrender," his father said.

"I just hope he went quickly," he added.

Wayne Driver said that later Tuesday, he would read a letter his son left for him before his death. He said that may provide some explanation about his son's actions.

Provincial police handled the investigation into Driver's shooting at the request of the Strathroy-Caradoc Police Service. The OPP and Strathroy-Caradoc police "continue to jointly investigate the incident" under the direction of the head of the OPP's criminal investigations branch, Tuesday's release said.

Trudeau comments on case

In his first public comments on the Driver case, Prime Minister Justin Trudeau said balancing individual rights with keeping Canadians secure from bombing threats has to be handled with care.

"All Canadians expect their government to do two things — to keep Canadians safe and to defend and uphold the values and rights that all Canadians hold dear," he told reporters in Nova Scotia, where he was making an infrastructure announcement.

"Getting that balance right isn't always easy in the challenging situation we now live in but it's extremely important."

Driver was under a peace bond for communicating with what the RCMP called well-known ISIS supporters in the U.K. and the U.S.

The RCMP said Driver had made a "martyrdom video" and was planning an attack in an urban centre during morning or afternoon rush hour.

Barriers to collecting digital evidence

Also Tuesday, RCMP Assistant Commissioner Joe Oliver would not answer a reporter's question about why the FBI learned of the "martyrdom video" first and then informed Canadian officials.

"I'm not going to get into operational matters are are currently undergoing investigation," he said during a press conference at a meeting of the International Association of Chiefs of Police.

When asked about the challenges of tracking and finding such videos, Oliver said law enforcement faces three issues when investigations involve digital evidence.

First, investigators must identify devices that might contain relevant evidence, then they have to obtain lawful permission to collect the evidence, and finally they must attempt to interpret that evidence.

"In some cases, when we have lawful authority and we do intercept communications between plotting criminals or terrorists, the difficulty that we face are sometimes those communications are encrypted and then we're confronted with the inability in some cases to interpret that data and make it into intelligible evidence that can then be used in a prosecution or court or an arrest or those types of things," Oliver said.

A funeral for Aaron Driver is being held on Thursday.