SAN DIEGO -- The federal government offered a second six-figure reward Thursday for information leading to the arrest and conviction of whoever gunned down a Border Patrol agent last month near the Mexican border in Campo.

The $250,000 bounty offered by U.S. Customs and Border Protection in connection with the murder of 30-year-old Robert Rosas Jr. of El Centro is in addition to a previous reward of $100,000 posted by the FBI and a $10,000 reward for tips resulting in the recovery of the slain lawman's stolen service pistol.

"Bringing those responsible for this heinous act to justice is of paramount importance for CBP and our law enforcement partners on behalf of Agent Rosas' family, friends and colleagues," said Jayson Ahern, acting commissioner of the agency.

On the night of July 23, Rosas was tracking a group of suspected illegal immigrants in the area of Shockey Truck Trail when he came under fire just north of the international boundary.

Blood evidence at the scene suggested that he managed to wound one of his attackers before collapsing.

Rosas, a father of two young children who had been with the Border Patrol for three years, died at the scene from gunshots to his head, neck and torso.

When fellow agents found Rosas lying mortally wounded near his patrol vehicle, his .40-caliber Heckler Koch P2000 duty handgun was missing.

Authorities asked anyone with information about the slaying to call the FBI's San Diego office at 858-565-1255.