FORT LAUDERDALE, Fla. (Reuters) - Prosecutors charged a Florida police officer on Wednesday in the shooting last July of an unarmed black man who was seen on cellphone video lying in a street with his hands in the air at the time he was shot in the leg.

North Miami Police Department officer Jonathan Aledda was charged with attempted manslaughter, a felony, and culpable negligence, a misdemeanor, according to the Miami-Dade State Attorney’s office.

The shooting of behavioral therapist Charles Kinsey, who was with and caring for a severely autistic man when he was shot, was one in a series of police shootings of black men across the United States to raise questions about police use of force and civil rights.

Aledda defended his actions last July, saying “I did what I had to do in a split second.” The Miami-Dade Police Benevolent Association, which is representing Aledda, was not immediately available for comment.

The officer was responding to reports of a man with a gun and apparently was aiming at the autisic man when he shot Kinsey, according to an affidavit supporting the arrest warrant filed with the state court for Miami-Dade County.

Kinsey had followed police commands and was lying on the ground at the time he was shot. He had been trying to get the autistic man back to a nearby group home from which he had wandered. Hilton Napoleon, a lawyer for Kinsey, was not immediately available for comment.

Initial calls to 911 emergency dispatchers reported a man, possibly suicidal, with a gun in his hand, which led to the arrival of 16 police officers, including Aledda. What a caller thought was a gun turned out to be a toy tanker truck held by the autistic man, according to the affidavit.

The affidavit said the autistic man, who is now 27 and has an IQ of 40, needed around-the-clock supervision.

In a video widely shared on social media, Kinsey can be heard yelling, “All he has is a toy truck in his hands.”

The affidavit said Aledda fired three shots using his personally owned Colt M4 Carbine rifle from about 150 feet (45 meters) where Kinsey lay.

“No other officer on the scene observed (the autistic man) exhibit any behavior that compelled them to shoot,” the affidavit says.