DIXON – The 9 mm semi-automatic rifle Dixon High School shooter Matthew A. Milby Jr. used Wednesday was purchased by his mother in 2012, investigators said Thursday.
The Illinois State Police are still determining how Milby had the weapon, and the agency also recovered surveillance footage from inside the high school, according to a release.
Milby, 19, was released from Dixon's Katherine Shaw Bethea Hospital about 10:20 a.m. Thursday and is being held in the Lee County Jail on $2 million bond. His arraignment is 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. His charges are 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.
Police and witnesses said the 19-year-old senior took the rifle to graduation practice in the Lancaster Gym about 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 officer-involved shooting is being investigated by the ISP.
"We are working with the [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 ISP Lt. Chris Endress, who identified the type of rifle Milby used.
Both of his parents, Dixon residents Julie Milby and Matthew A. Milby Sr., have been interviewed, and a search of his mother's Everett Street home, where the younger Milby lives, was conducted Wednesday, 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 is legally barred is from owning guns.
Milby Jr. was charged May 15, 2017, and convicted 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 this 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 representative to be with an officer 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."
May 11 was the last day of school for the senior class; graduation practice resumed at 1 p.m. Thursday 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, Dixon School District 170 officials said.