A Florida man who was angry that his 7-year-old stepson got out of bed to get a cookie brutally beat the boy and left him in bed to die, the authorities said on Tuesday.

The man, Jack J. Montgomery, 31, who faces charges of first-degree murder and child abuse, called 911 at about 10:50 a.m. on Saturday to report that his stepson, Brice Russell, would not wake up and was not breathing in their room at a hotel in Seffner, Fla., about 20 miles east of Tampa, the Hillsborough County Sheriff’s Department said in a statement on Tuesday. Mr. Montgomery had been watching over the boy and three siblings at the hotel while their mother worked, the department said.

When medics arrived at the hotel, they found the boy lying in bed. He was pronounced dead just before 11 a.m., the sheriff’s department statement said.

Investigators said that Mr. Montgomery had “punched the child in the face, mouth and stomach with a closed fist, threw the victim around the hotel room and shoved his face into the carpet,” the statement said. It said that the other children told the investigators they were threatened with violence unless they also hit Brice, and one child did.