The San Mateo County District Attorney’s Office today opted not tofile attempted murder charges against a 21-year-old man arrested on suspicion of shooting another man in front of his son in San Mateo last weekend. “Based on a follow-up investigation, the evidence did notestablish his identity as the person who shot the victim,” Chief DeputyDistrict Attorney Steve Wagstaffe said of Christian Torres, the man arrested for the Saturday night shooting.The district attorney’s office had until 11 a.m. today to file charges against him but ultimately declined to based on a lack of evidence.Officers responded to a report of shots fired at about 9:45 p.m. in the 300 block of Grand Boulevard and found the victim suffering from gunshot wounds, San Mateo police Sgt. Bob Szelenyi said. Investigators determined that the victim was standing with his son in their driveway when a male walked by. Szelenyi said words and gestures were exchanged regarding gang affiliation and the male was told to leave.He left but soon returned in a car containing several people, one of whom was armed with a shotgun.Three or four people got out of the car and the one with the shotgun fired down the driveway, striking the victim, Szelenyi said.The victim was transported to Stanford Hospital and was expected to survive, according to Szelenyi.Wagstaffe could not confirm whether Torres had been released from jail.