Hours before mowing down pedestrians with a van in a busy Toronto street on Tuesday, 25-year-old Alek Minassian had posted a 'cryptic' message on Facebook, police said.
In one Facebook post, Alek praised a man who killed six college students in California in 2014, before taking his own life, newstalk.com reported.
The Toronto Police have suspected that the post might have inspired Alek to carry out the attack.
Meanwhile, the nationalities of the four victims have been identified by the police.
According to CBC, the first victim to be identified was Anne Marie D'Amico, an American national who worked at Invesco, a US-based investment management firm in Toronto.
D'Amico's colleague at Invesco, Jon Tam told, CBC's Metro Morning, "She was a very warm, friendly presence in the office. Always smiling. I'll definitely be missing seeing that smile around the office."
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The Jordanian Embassy in the city confirmed that its national was killed in the van attack.
Meanwhile, according to Yonhap and South Korea's Foreign Affairs Ministry, two of its nationals were confirmed dead, while three more were unaccounted for.
On Monday, the Toronto van rampage at Yonge Street claimed at least 10 lives and left 15 others injured.
The accused has been charged with 10 counts of first-degree murder. He is also facing 13 counts of attempted murder. The motive behind the attack is yet unclear.
Canadian Prime Minister Justin Trudeau offered condolences to the loved ones of those who were killed.