A Long Island state trooper hailed as a hero last fall was charged on Monday with staging a shooting that set off a manhunt for a nonexistent suspect, according to Nassau County prosecutors.

Thomas J. Mascia, 27, had told authorities that a gunman had shot him in the leg during a traffic stop, according to a criminal complaint — a report that shut down a major road and terrified the public, prosecutors said. Investigators later discovered that Mr. Mascia had actually shot himself, prosecutors said. He was charged with falsifying evidence and lying to law enforcement.

In the West Hempstead home that Mr. Mascia shared with his parents, officers discovered a Smith & Wesson semiautomatic rifle with illegal modifications, according to the criminal complaints. His parents, Dorothy R. Mascia, 55, and Thomas Mascia, 62, were charged with possession of a firearm, a felony, prosecutors said. The rifle was not connected to the charges against Mr. Mascia.

The senior Mr. Mascia, a former New York City police officer, is a felon who is not allowed to carry a gun, according to prosecutors and public records. Mr. Mascia — who was charged in 1992 for illegally buying and selling cocaine in a corruption scandal that led to sweeping police reforms — was fired in 1993 after pleading guilty to conspiring to distribute the drugs.

All three Mascias turned themselves in Monday at a New York State Police headquarters in East Farmingdale on Long Island — the same place where Mr. Mascia had worked until his recent resignation.

“He knew the depth and breadth of the response that comes with an officer shooting,” Anne T. Donnelly, the Nassau County district attorney, said at a news conference on Monday at Nassau County Courthouse in Mineola.