Rosas, a three-year Border Patrol veteran, had a 2-year-old son and an 11-month-old daughter.
An autopsy report says a Border Patrol agent who was slain near San Diego was shot eight times in the head, neck and torso.
The San Diego County medical examiner's office report released Tuesday says 30-year-old Robert Rosas was hit four times in the head -- three times on the left side of his face and once in the back of the head. He was also shot once in the neck and three times in the torso.
The report says Rosas was discovered the night of July 23 in Campo, Calif. without a pulse. It says he left his car with the ignition on while pursuing three suspected illegal immigrants.
The 30-year-old agent was killed while responding alone to a suspected border incursion near Campo.
U.S. Customs and Border Protection is offering a $250,000 reward in addition to the $100,000 put up by the FBI for information leading to the arrest and conviction of the killer(s). The FBI has also said anyone with information leading to the recovery of Rosas' missing black Heckler Koch (HK) P2000 .40 caliber service pistol would be eligible for a $10,000 reward.
In the week after the slaying, Mexican authorities named a man they accused of murdering Rosas. The country's federal police said the alleged gunman was Ernesto Parra Valenzuela, 36, who was arrested in Tecate. At the time, it was reported that Valenzuela was carrying a Border Patrol-issued pistol, but the FBI said they are looking for a different weapon than one shown in a photograph taken after Valenzuela's arrest.
Mexican police also announced the arrests of four men in July near Tecate who are suspected of involvement in the fatal shooting. U.S. investigators also arrested three people at a San Jose, Calif., hospital, but it's not known what role they may have played in the killing.
Mexico police did not say what evidence they had against the four, whom they identified as Jose Quintero Ruiz, 43, and his brother Jose Eugenio Quintero Ruiz, 49; and taxi drivers Jose Alfredo Camacho, 34, and Antonio Valladares, 57.
Anybody with information concerning this case is being urged to contact the FBI at 858-565-1255. Tipsters can remain anonymous, according to the officials with both organizations.