DIXON – The 9mm semi-automatic rifle Dixon High School shooter Matt A. Milby Jr. used Wednesday was purchased by his mother in 2012, investigators said.
The Illinois State Police is still determining how Milby had the weapon, and the agency also recovered surveilance footage from inside the high school, according to a release.
Milby, 19, was released from KSB Hospital about 10:20 a.m. Thursday and is in Lee County Jail on $2 million bond. His arraignment is tentatively scheduled for Friday.
Milby, who was shot in the shoulder while trying to flee, is charged with three felonies, "and more charges may be filed in the near future," Dixon police said in a news release.
The 19-year-old senior took a 9mm rifle to graduation practice in the Lancaster Gym around 8 a.m. Wednesday, fired shots into the gym and took off running when confronted by school resource officer Mark Dallas.
Milby shot at Dallas as they were running; Dallas returned fire.
The ISP is investigating the officer-involved shooting.
"We are working with the ATF (Bureau of Alcohol, Tobacco, Firearms and Explosives) to track the original purchaser of the weapon that was used and make sure we can figure out how it got in his hands," said Lt. Chris Endress, who identified the type of gun Milby used.
Milby is charged with aggravated discharge of a firearm, aggravated discharge at a school employee, and aggravated discharge at a school building, each punishable by 6 to 30 years in prison. There's no word yet on when he will make his initial appearance.
Both of his parents, Dixon residents Julie Milby and Matthew A. Milby Sr., have been interviewed, and a search of his mom's Everett Street home, where Milby lives, was conducted Wednesday afternoon, Endress said.
Julie Milby told reporters after the shooting that she did not know where her son got the gun, and that they did not have guns in their home.
The senior Milby is a convicted felon and so presumably is not allowed to own guns. He was charged May 15, 2017, and found guilty April 26 in Lee County Court of possession of less than 10 grams of marijuana, and fined $120.
As with any officer-involved shooting, investigators ask for a voluntary statement from the officer, which usually is given with a representative of the officer's union present.
In the case, "the logistics of when everyone is available has not been determined," Endress said.
Dallas, who is being lauded as a hero for his immediate and decisive actions, will not be available for media interviews until after his ISP interview, Dixon police officials have said.
It's common for a union rep to be at the officer's side during the course of an investigation, to act a liaison and to "look out for the best interest of the officer," Endress said.
The Fraternal Order of Police responded quickly Wednesday, and a representative was with Dallas shortly after the shooting, Endress said.
Endress also had high praise for the way all involved responded to the crisis.
"As an outside agency, it was absolutely amazing to to see all the resources come together and work so quickly to seal off and secure the school, to relocate the students and reunite the students with their parents, and secure the crime scene. It was very well organized and orchestrated, under those circumstances.
"It was clear to us that the school and the city and the county had planned for this day."
Friday was the last day of school for seniors class; graduation practice resumed today at 1 p.m. in the gym. The ceremony is 2 p.m. Sunday.
Counselors will be available through Tuesday, the end of the school year, for all students and staff, school district officials said.