A dead body found on fire inside a burning building had been decapitated, Birmingham police said Saturday.

Police spokesman Sgt. Rod Mauldin said a person of interest was in custody but no charges had been announced.

The victim’s body was found Thursday after office workers spotted smoke coming from a vacant building across the street, al.com reported. Police and firefighters found the body burning inside.

Mauldin said investigators believe there was some kind of argument before the victim was killed, decapitated and set on fire. The victim was a man but has not been identified, said Jefferson County Chief Deputy Coroner Bill Yates.