ORANGE PARK, Fla. -- A 21-year-old man is accused of beating his 19-year-old girlfriend to death with a baseball bat Thursday night then dumping her body into a pool.

According to the Clay County Sheriff's Office, Joshua Maulsby was arguing with Alicia Kay Castaneda at his home on Epsilon Court, between Kingsley Avenue and Doctors Lake Drive in Orange Park, just after 9 p.m.

After the woman reportedly threw shoes at Maulsby, he allegedly hit her with his fist. According to the arrest report, he then went out to his car and got a baseball bat, went back inside and struck Castaneda several times in the head.'

Maulsby told investigators that he thought Castaneda was dead, so he dragged her out the back door and threw her into the pool.

A some point, Maulsby's mother pulled Castaneda out of the pool and tried to give her CPR, then called police.

Maulsby was still in the house when deputies arrived and took him into custody. The arrest report said Maulsby had an abrasion on his right hand and blood splattered on his legs and feet.

Maulsby was charged with murder and booked into the Clay County Jail.

"Alicia was extremely bright, friendly, funny, generous, sensitive, compassionate, warm and loving," Castaneda's mother, Gwen Harvey, said in a statement. "Her beauty radiated inside and out. We all adored her more than words can ever say."

The couple were both graduates of Orange Park High School, where he was a star wrestler and she had an interest in journalism, which she was pursuing at the University of Central Florida.

"They'd been almost inseparable for the last nine months -- spending time together," Maulsby's father, Ken, said Friday.

The elder Maulsby said he spoke out so the public knows his son is mentally ill.

"I think he realized he did something, but I don't really think he understood the repercussions," Maulsby said.