Authorities said Monday they are searching for a new suspect in the killing of a Miami police detective who was shot with an assault weapon.

Andrew James Rolle, 20, was named by North Miami Beach police as the new suspect in the Jan. 8 slaying of James Walker, a detective with the Miami Police Department. Rolle had been arrested Jan. 5 on misdemeanor loitering and prowling charges but was released on $500 bail, according to jail officials.

Further details were expected at an early afternoon news conference, said North Miami Beach police spokesman Warren Hardison.

Walker, 30, who was off duty at the time, was found slumped over the wheel of his unmarked police car with his service weapon in his hand. He had been shot multiple times and an AK-47 assault rifle was found at the scene outside a North Miami Beach apartment complex.

Police initially identified the main suspect as Ricardo Ajuste, 21, who had been arrested early Wednesday after allegedly opening fire on a couple in a car near Walker's vehicle.

Ajuste, identified by police as a gang member, has been charged with two counts of attempted murder in that shooting but was never charged in Walker's death.

It was not immediately clear why Rolle is now the main suspect, but apparently Ajuste is no longer considered the shooter. Rolle's whereabouts also were not known.

Walker, who was in the area to visit his wife, was buried Saturday.