MADISON, Wis. (AP) — An inmate found dead at a maximum-security prison in northeastern Wisconsin was strangled, investigators said Thursday.

Brown County Sheriff’s Office deputies and medical personnel were called to the Green Bay Correctional Institution on Tuesday evening for a report of a pulseless inmate who wasn’t breathing. They found 19-year Micah Laureano dead at the scene. It’s unclear exactly where in the prison Laureano was found.

The sheriff’s office said that an initial investigation determined that Laureano had been killed in his cell and his 24-year-old cellmate was a suspect.

The sheriff’s office said in an updated news release Thursday that an autopsy revealed Laureano had been strangled.

Laureano and the suspect had been together in the cell for only hours before his death, the sheriff’s office added. The release did not say specifically how long they had been together.

The investigation is ongoing and charges are expected to be filed late next week, the sheriff’s office said.