Shawn O'Neill, 34 at the time, was armed with a kitchen knife when he forced his way past a 17-year-old babysitter into Davis's Brampton home on Dec. 20, 1987. Davis, who was 58 years old at the time, picked up a fireplace poker and successfully chased O'Neill out of the house, police reported at the time.
Davis, the babysitter and Davis's grandchildren were unharmed.
Davis was Ontario premier until 1985.
At his trial, both the Crown and judge agreed there was likely a "degree of insanity" involved in O'Neill's actions.
O'Neill was jailed for two years for the break-in. A psychiatric report submitted during that trial said O'Neil was a chronic paranoid schizophrenic who "entertains violent fantasies concerning political figures." O'Neill said at the time he was "obsessed" with harming Davis and compared himself to John Hinkley, who attempted to assassinate then-U.S. President Ronald Reagan.
O'Neill appears to have another encounter with the law in August 1996, when he was charged with assault with a weapon and pointing a firearm. O'Neill was found not criminally responsible due to being mentally unfit.
On Sunday, four people were stabbed along a stretch of a downtown Toronto street near the former Maple Leaf Gardens after police reported O'Neill "went on a bit of rampage."
O'Neill, now 62 years old, faces 20 charges, including four counts of attempted murder, four counts of aggravated assault and six counts of assault with a weapon.