A San Francisco police sergeant testified Tuesday morning in the trial of Edwin Ramos, an alleged MS-13 gang member accused of murdering a father and two of his sons in San Francisco's Excelsior District in 2008.

Ramos, 25, of El Sobrante, is charged with fatally shooting Tony Bologna, 48, and his sons Michael, 20, and Matthew, 16, near Congdon and Maynard streets the afternoon of June 22, 2008.

San Francisco police Sgt. Joshua Phillips from the department's crime scene investigation unit was the first witness to take the stand.

Phillips said that when he arrived at the scene of the shooting, he found shattered glass from the Bolognas' Honda in the street, and saw what appeared to be the victims' blood on the hood and front passenger side window of the car.

Assistant District Attorney Harry Dorfman, who is prosecuting the case, said during his opening statements on Monday that he plans to bring Andrew Bologna, the only one of Tony Bologna's sons to survive the shooting, to testify later this week.

Dorfman said Ramos, who he said is known within the MS-13 gang as "Popeye," shot the Bolognas after mistaking them for rival gang members and that the shooting was in retaliation for the shooting of Marvin Medina, a fellow MS-13 gang member, earlier that day.

Defense attorney Marla Zamora countered in her opening statement on Monday that it was Wilfredo "Flaco" Reyes who fired the gun, surprising Ramos, who was driving the Chrysler 300 sedan that was later identified as the car used in the shooting.

Zamora said Andrew Bologna might not actually have seen the shooting because he ducked when shots were fired.

Reyes remains at large. Zamora said Monday that the case is about "how the government and MS-13 made Edwin Ramos the fall guy."

The case drew criticism of San Francisco's sanctuary policy, which shielded illegal immigrant juveniles suspected of crimes from being reported to federal immigration agents.

Ramos is an illegal immigrant from El Salvador who moved to the U.S. in 2000. He had contact with San Francisco police as a juvenile but was not reported to U.S. Immigration and Customs Enforcement.

The city has changed its policy since the murders. The Bologna family also sued the city over the sanctuary policy but a judge later dismissed the suit.

Testimony is expected to continue throughout the day today. The trial is expected to last for months.