DAYTON, Ohio (AP) — Authorities who have been trying to piece together a motive and other factors that led to a deadly mass shooting in Ohio will provide an update Tuesday on their findings.

Dayton officials scheduled a news conference, a day after federal authorities announced charges against a longtime friend of gunman Connor Betts. Ethan Kollie is accused of lying on federal firearms forms while buying a pistol not used in the shooting.

Police say Betts killed nine people, including his sister, and wounded at least 14 more people Aug. 4 before they killed him. Investigators haven't released a motive for the early morning shooting in the busy Oregon entertainment district.

Kollie bought armor and a 100-round magazine for Betts, authorities said. But they said there was no evidence he knew what Betts planned.

Kollie will appear Wednesday in federal court. His attorney said he has been cooperating with investigators.

"He was as shocked and surprised as everyone else that Mr. Betts committed the massacre," attorney Nick Gounaris said Monday.

Prosecutors accused Kollie of lying about not using marijuana on federal firearms forms in the purchase of a pistol that wasn't used in the shooting.

Possessing a firearm as an unlawful user of a controlled substance is a federal crime punishable by up to 10 years in prison. Making a false statement regarding firearms carries a potential maximum sentence of up to five years' imprisonment.

Police have said there was nothing in Betts' background to prevent him from buying the gun.

The weapon was purchased online from a dealer in Texas and shipped to another firearms dealer in the Dayton area, police said.

Ohio Republican Gov. Mike DeWine last week proposed a package of gun-control measures , including requiring background checks for nearly all gun sales in Ohio and allowing courts to restrict firearms access for people perceived as threats.

Two state lawmakers Monday reintroduced legislation that would restrict access to guns. One bill would establish universal background checks. The second would raise the minimum age for all gun purchases to 21.