A report filed Tuesday revealed more details about the attack that left a 7-year-old dead and the welfare check by deputies that possibly could have saved his life. 

According to the Hillsborough County Sheriff's Office, Brice Russell was killed Saturday morning when he was beaten by Jack Junior Montgomery, his mother's boyfriend. 

Montgomery, 31, is charged with first-degree felony murder and aggravated child abuse. Investigators say Montgomery called 911 Saturday morning after his stepson would not wake up.

Investigators say Montgomery punched his stepson in the face, mouth and stomach. They said he also threw the boy around the motel room and shoved his face in the carpet.

According to the report, a deputy responded to a welfare check Saturday morning at the Masters Inn on State Road 579 in Seffner, where the family was living. 

But the deputy did not go inside the motel room where the child had recently been beaten and was unconscious. 

The other children in the room later told deputies Montgomery threw Russell against a shelf. They said the 7-year-old was bleeding from his mouth and never woke up.

The Medical Examiner's Office determined Russell died as a result of homicidal violence.

The arrest warrant states that witnesses at the motel reported hearing the beating as it was happening. Guests told deputies that heard loud thumps coming from the room and a man screaming "beat the kid and push the kid over here."

Montgomery threatened to harm the other children if they didn’t join in the beating, investigators say. Out of fear, one of the children hit the boy.

When the deputy responded to the welfare check, the arrest warrant said Montgomery only opened the door a tiny bit and the deputy did not go inside the room.