DELRAY BEACH, Fla. -- A Delray Beach dad was arrested Thursday after he admitted to throwing his 9-month-old son into a canal, police said.

Police said Charles Edward Tyson accused girlfriend Shameka Mosley of cheating on him and got into an argument with her while they were driving.

Mosley, 17, said Tyson, 20, dangled their baby boy out of the car window and dropped him. Mosley said she jumped out and grabbed the baby, but she and Tyson struggled again. She said Tyson then grabbed the baby by one leg and slammed him into the hood of the car. Police said the impact left a dent in the hood.

Mosley said she got the baby and put him into the back seat of the car, but before she could get in with him, Tyson sped off.

Tyson later returned and told Mosley that he had tossed the child into the C-4 Canal, west of Congress, police said.

Residents of the neighborhood called police when Mosley began screaming hysterically.

Police discovered the boy's body west of Interstate 95 near Congress Avenue, about 100 yards south of where Tyson admitted to tossing the child. The boy apparently drowned.

"He told me he was going to kill my child," Mosley said. "He had mental problems but I didn't know he was going to turn out to do that to the baby."

Tyson is charged with first-degree murder, aggravated child abuse and child endangerment. He was being held at the Palm Beach County jail.