The FBI's request signals that the
McAuliffe said the gun, a 9-millimeter semiautomatic, won't be returned until the department completes its investigation and had no further need for evidence in the case.
Zimmerman's acquittal Saturday unleashed protests across the country, including appeals to the Justice Department to vigorously pursue civil rights charges against Zimmerman.
Zimmerman told police he shot Martin in self-defense after Martin punched him in the nose and pounded his head against the sidewalk.
Martin supporters were disturbed by the idea that police would return to Zimmerman the same gun he used to kill Martin.
But two days after police received the evidence in the case from the Seminole County Clerk of Courts - including the gun, Martin's clothes and the Skittles and iced tea Martin was carrying when the fatal altercation began - that plan is now on hold.
McAuliffe said the gun was locked up in a "very secure" spot within the police department.
"It wouldn't be in my desk drawer," he said.