The body, also missing an arm, was discovered Sunday evening, the Houston Chronicle reported.
As police investigated, they discovered a trash bag containing the missing head and arm underneath a home next door with a chainsaw next to the bag, the newspaper said.
Police said they were questioning a man who lives at that house, who reportedly is the victim's roommate.
Lucinda Watkins, who lives next door to the home where body parts were found, said she heard two gunshots just after 10 p.m. Saturday.
On Sunday, a woman called police and said there was a body in the back yard of the vacant house,
Police said they are questioning that woman.
The identities of the victim and those being questioned had not been released, the Chronicle reported.