Riverview, Fla. -- An 18-year-old man planned to kill his mother and stepfather, but she came home first Monday and was killed with a baseball bat and butcher knife on her birthday.

Joshua Leon Carmona, 18, is charged with first-degree murder. He is being held without bond at the Falkenburg Road jail.

His mother -- Tahirih Lua D'Angelo, 39 -- was found by a relative in her townhome with upper body trauma. The sheriff's office was called about 4 p.m. Monday.

After killing his mother, Carmona took her car, picked up his 3-year-old sister from day care and handed her off to one of his friends. By then deputies were looking for the car.

The car was spotted about 9:30 p.m. near Interstate 275 and Livingston Avenue, and deputies pulled him over. Carmona complied with commands, and confessed to the killing while in the deputy's cruiser, according to the sheriff's office. Carmona mentioned that there were ongoing family issues.

Detectives are asking anyone with information to call the sheriff's office at 813-247-8200.