When police arrested 34-year-old Nhan Lap Tran after the February rampage, they found a note in his bedroom that read, "Random Kill, Fake Plates," the St. Paul Pioneer Press reported ( http://bit.ly/13Mwdyh).
The date "12/12/12" was also scrawled all over the walls of the bedroom, according to the affidavit filed in Washington County District Court.
Tran is charged with six felonies, including second-degree intentional murder and second-degree murder during an assault. He had previously admitted to the shootings but hadn't given a motive, prosecutors said.
Tran's attorney, Susan Drabek, did not immediately return a phone call to The Associated Press for comment Saturday.
The shooting rampage happened shortly after 6 p.m. on Feb. 11 in the St. Paul suburb of Oakdale, a few yards from Tran's home. Fourth-grader Devin Aryal died in the shootings, and his mother and another woman were wounded. Two other motorists escaped as they were being fired upon, according to the criminal complaint.
Tran told investigators that "cars had been following him around for a while, and the persons driving the cars had been revving up their engines while parked in front of his house waking him up," the affidavit said. "Nhan Tran said this is why he shot at the cars tonight."
Prosecutors said Tran had roughly 200 rounds of ammunition stuffed into his jacket pocket, a backpack and the fanny pack he was wearing when arrested several blocks away.
He was also carrying two loaded 9 mm magazines and two large knives at the time. A loaded 9 mm handgun with a bullet in the chamber was found just feet from him. He admitted he tossed the gun aside when he saw authorities closing in, the criminal complaint said.
During Tran's first court appearance in February, his public defender requested a mental health evaluation. A review hearing is scheduled for March 25.
Information from: St. Paul Pioneer Press, http://www.twincities.com