The bullet riddled body of a man was found in a Sonoma County beach parking lot last week. Authorities say the man was a protected witness, and he was kidnapped and killed to prevent him from testifying against alleged gang members.

Four Santa Rosa-area men were arrested Sunday and charged with murdering Vutha Au, 24. The charges carry special enhancements that accuse them of killing a witness to prevent him from testifying and of being gang members.

Because of the special enhancements, Quentin Glenn Russell, 24, David Prak, 19, Sarith Prak, 21, and Preston Phongsuvane Kahoone, 22, could face the death penalty if convicted.

Two other men: Tyrone Rosenblad Tay, 26, and Jack Houmpheng Sendsourith, 29, were arrested on suspicion of the murder of Vutha Au Thursday.

Au's body was discovered early Sunday morning by a state park ranger. Au was shot nine times, according to the county coroner. The angles of the wounds indicate that he may have been killed by multiple shooters.

The four men currently charged with the crime were pulled over and arrested about 10 miles from the scene of the crime shortly after the body was discovered.

Vutha Au's brother, Terry, was kidnapped and tortured in 2006 by alleged gang members, and Vutha Au was expected to testify in the case, prosecutors told the San Francisco Chronicle. Two of the three defendants in the kidnapping case are the brothers of Preston Phongsuvane Kahoone, one of the four men charged with murdering Vutha Au.

All four murder suspects are being held without bail.