The man charged with killing 10 people in the Toronto van attack last year is refusing to help police unlock three of his personal electronic devices, court documents obtained by CBC News show.

For the last year, Toronto police have been trying to access Alek Minassian's MacBook laptop and two smartphones — but so far, haven't had any success.

Investigators believe his locked devices may lead to other like-minded men considering violent attacks.

Minassian, who studied software development and was weeks away from graduating from Seneca College's computer studies program, added layers of encryption to his devices and is refusing to give up his passwords, Det. Christopher Sloan said in a May 2019 affidavit.

Officers have been trying to unlock Minassian's laptop by "applying a large number of passwords in succession by automation in the hopes that the password for the device can be … discovered," Sloan wrote.

"Absent the password ... it is virtually impossible to predict how long it will take," he added, "because the password possibilities are almost infinite."

Sloan, the head of Toronto's Technical Crimes Unit, says investigators have been searching the devices for evidence ahead of Minassian's trial, which is set for February 2020. Police have also accessed data from at least two dozen other devices seized from the Minassian home.

Police are seen near the damaged van in the aftermath of the attack on April 23, 2018. (Aaron Vincent Elkaim/Canadian Press)

Minassian, 26, is charged with 10 counts of first-degree murder and 16 counts of attempted murder. He drove a rented van onto a north Toronto sidewalk, mowing down bystanders on April 23, 2018. The trial is expected to focus on his state of mind.

In a police interview on the day of his arrest, Minassian told a detective he had used his encrypted laptop to check his emails just hours before the attack. He also posted a message on Facebook using his Asus ZenFone 4 smartphone, linking him to the incel community.

"The Incel Rebellion has already begun!" he wrote on Facebook.

Incels ("involuntary celibates") are an internet subculture dominated by men frustrated by their lack of success with women, who often express extreme feelings of misogyny and hatred.

Minassian told a detective he has been part of the group for years and had communicated with Elliot Rodger, a hero to many incels who killed six people and injured 14 others near the University of Santa Barbara, Calif., then killed himself, in 2014.

Sloan said his officers have reached out to other police services — including the RCMP and Ontario Provincial Police — private security firms and Apple.

"Apple has advised that it does not store device-specific passwords and is not aware of any other bypassing method," Sloan wrote in the court document. "As such, Apple is unable or unwilling to offer assistance."

Steven Penney, a University of Alberta law professor, says accessing data on electronic devices in serious criminal investigations is a problem for police around the world.

Minassian posted a message on Facebook shortly before the attack. (Twitter)

"The problem is that our laws, in my view, have not really kept up with the nature of the technology," he told CBC News.

"Parliament should consider passing a new law that would allow the police in limited circumstances to compel someone to provide a password but only for data that the police are already in lawful possession of," he said.

But David Skillicorn, a professor in the School of Computing at Queen's University in Kingston, Ont., isn't convinced legislation will help force people on trial to unlock their phones.

Steven Penney of the University of Alberta says Parliament should consider a law that would compel someone to provide passwords. (Submitted by Steven Penney)

"I don't see how it could be done," Skillicorn told CBC News. "It's always been true that criminals have had information that the police would have loved to have and had no way to get.

"If you want to say to a criminal you must unlock your phone, then what's the leverage to make the criminal do that? There simply isn't one."

Last month, a Crown lawyer with the Ministry of the Attorney General confirmed to CBC News that police have had "no success in unlocking the computer and phones as of yet, but [are] still trying."

The attorney general's office said in a statement Thursday that it would no longer comment on any evidence with the trial set to start early next year.