SAN ANTONIO - The death of an 8-month-old boy found buried in a backpack in a San Antonio field last month has been ruled a homicide.

The Bexar County Medical Examiner’s office said Friday that King Jay Davila died of blunt force trauma.

His 34-year-old father, Christopher Davila, told authorities Jan. 4 that his son was abducted when his car was stolen from a convenience store. However, police said they didn’t believe his story and a week later, Davila led investigators to the child’s body. According to an affidavit, Davila said the child died after falling off a bed.

Davila has been jailed on charges including injury to a child. His mother and cousin are also jailed, facing charges of tampering with evidence.

Police say charges could be upgraded when the investigation is complete.