BANGOR, Maine — A local man is in Penobscot County Jail waiting to be arraigned on charges that he assaulted a 1-year-old child, Bangor police said Tuesday.

Matthew McMahan, 21, was arrested Monday after a police investigation that started 13 days earlier. On March 18, Bangor police received a report of a child who was hospitalized with a “suspicious injury,” according to a news release from Bangor police Sgt. Cathy Rumsey.

The child suffered severe bruising to the back of his head, according to Rumsey. The injuries weren’t life threatening.

A caseworker from the Department of Health and Human Services, a representative of the Spurwink Child Abuse Clinic and a Bangor police detective collaborated on the investigation that followed.

“McMahan was dating the mother of the child and living in their home when the injury occurred,” Rumsey said.

McMahan faces a charge of Class C felony assault. The charge reaches the felony level because the child assaulted was younger than 6. His arraignment date has not yet been set, according to Rumsey.