NASHVILLE, Tenn. (WKRN) — A man beat his teenage stepbrother to death at a Tennessee home, while the boy’s mother watched and did nothing to stop it, an arrest warrant alleges.

Rebecca Greenwood, 52, and David Matheny, 33, were booked taken to jail Saturday morning on charges of criminal homicide.

Police said Greenwood called 911 just before noon Friday to a report finding her 14-year-old son, Sayeed Nelson deceased at their Nashville home.

An arrest warrant states Greenwood claimed Sayeed, who has autism, had fallen in the shower the day before and hit his head. She said she and Matheny, her stepson, checked on the boy multiple times that day, then went to a bar for drinks and checked on him again before going to bed that night, according to the paperwork.

Greenwood explained she and Matheny went to the grocery store the next day to buy cleaning supplies and get food, police said. She stated they cleaned the residence, then went to check on Sayeed, who they found unconscious, so Greenwood called 911.

Sayeed was pronounced dead at the residence. Upon further investigation, police determined the teenager’s injuries were not entirely consistent with a fall.

Detectives questioned Greenwood, who they said admitted she had watched as Matheny punched the teenager and “stomped on his head” during an altercation. She explained she told Matheny to stop, but walked away without making sure the attack had ended, according to police.

Officers added the mother and her stepson cleaned the residence to get rid of evidence of the attack, so they were each charged with one count of evidence tampering.

Greenwood was also charged with child neglect, while Matheny was charged with child abuse.

No bond was set for either suspect on the criminal homicide charges.