According to the NY Daily News, a Phoenix teen has been arrested and charged with 1st degree murder in connection with the beating death of his girlfriend’s 3-year-old daughter.

Martwane Mackey, 18, is also charged with beating Ty’Shea Austin’s 1-year-old sister, Zariah, but the toddler survived. Mackey’s girlfriend, Qnique Thues, was at work at the time. The couple lived together.

Mackey waited hours before calling 911 from a pay phone on Sunday. When police arrived, they found Mackey holding a limp Ty’Shea in his arms.

Mackey admitted to biting and slapping Ty’Shea to revive her after she had a “choking and respiratory incident” at home. He denied killing her.

Officers saw bruises and bite marks on Ty’Shea’s head and body, and police say little Zariah had similar injuries. She was hospitalized and is in stable condition.

“He’s a monster, and people need to know he’s a monster,” Rhonda Brown, Ty’Shea and Zariah’s grandmother, told ABC 15 News. “I don’t think death is good enough for him, I think he needs to be beaten like he beat her.”

The family can’t afford to pay funeral expenses to bury Ty’Shea. Donations can be made through any Wells Fargo branch to the Ty’Shea and Zariah Memorial Fund, or via the account number 9373518860.