Authorities are working to piece together what led to a mass shooting in Ohio after accusing the gunman’s friend of buying body armor used in the massacre.

Dayton, Ohio, officials plan an update on the investigation at a news conference Tuesday afternoon.

Federal authorities announced charges Monday 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.

They also accused Kollie of buying armor and a 100-round magazine for Betts. They said there was no evidence he knew what Betts planned.

Police say Betts killed nine people including his sister on Aug. 4 before they killed him.

Kollie will appear Wednesday in federal court. His attorney says Kollie was shocked by the shooting.

(AP)