Prosecutors have formally charged a 21-year-old man suspected in some of the freeway shootings that have rattled the Phoenix area.

Leslie Allen Merritt Jr. was charged with 16 counts including aggravated assault, unlawful discharge of a weapon, disorderly conduct, endangerment and carrying out a drive-by shooting.

Authorities say they have tied him to four of the 11 shootings based on ballistics tests. State police say copycats might be shooting guns or other weapons on freeways, so the investigation remains open.

Merritt says he’s innocent and didn’t have the gun at the time of the shootings, which started in late August. He is in jail and has a court hearing scheduled for Friday. Authorities say a series of freeway shootings that rattled the Phoenix area started two days earlier than previously believed.