Same Firm Did Checks on Snowden and Gunman WASHINGTON - A company that conducted a background check of Edward J. Snowden, the government contractor who leaked national security secrets, said on Thursday that it had also run a check on the former Navy reservist who killed 12 people at the Washington Navy Yard on Monday. USIS, once known as US Investigations Services, said that it conducted the check on the reservist, Aaron Alexis, in 2007; Mr. Alexis joined the Navy that year. The company said in a statement that it could not disclose the reason for the check or the results because "we are contractually prohibited from retaining case information gathered as part of the background checks." Mr. Alexis had a clearance that allowed him to get an access card needed to get on the Navy base. The company also said that in 2011, it performed a "periodic reinvestigation" of the clearance for Mr. Snowden, who is now wanted by the United States for leaking details of the National Security Agency's surveillance programs. The Office of Personnel Management has been investigating the company since late 2011, Michelle B. Schmitz, assistant inspector general for investigations, said at a Senate hearing in June. The disclosures came as the director of the F.B.I., James B. Comey, said that Mr. Alexis was "hunting people to shoot" as he made his way through the building but did not appear to have targeted a particular person or group of people. "He emerged from the bathroom a few minutes after 8 with the shotgun and proceeded to almost immediately, after coming out of the bathroom, to shoot folks on the fourth floor in a way with no discernible pattern," Mr. Comey said Thursday. And, it appears to me he was wandering the halls and hunting people to shoot. Mr. Comey, who spoke at F.B.I. headquarters here, said that Mr. Alexis drove into the navy yard around 8 a.m. on Monday and went right to a bathroom on the fourth floor, carrying a bag. Moments later, Mr. Alexis exited with the shotgun. Although the butt and the barrel of the gun had been partly sawed off, Mr. Comey said he did not know whether Mr. Alexis had the shotgun in the bag or had previously hidden it in the bathroom. Despite previous accounts from law enforcement officials that Mr. Alexis fired down on people sitting in an atrium on the third floor of the building, Mr. Comey said there was no evidence that he had done that. He added, "He shot folks on the fourth floor, the third floor and then went down to the lobby and shot a security guard." After shooting the guard, Mr. Alexis took the guard's handgun and headed back upstairs, where he continued to shoot people with the shotgun, Mr. Comey said. Mr. Alexis, who kept some ammunition in a pocket of his cargo pants, began using the handgun after he had used all of the shotgun's ammunition. Mr. Comey said that people from different backgrounds and parts of the building were shot, leading him and investigators to believe that Mr. Alexis might not have been targeting a particular person or group, like co-workers. About a half-hour after Mr. Alexis started shooting, a heavily armed team from several agencies arrived, Mr. Comey said. A "sustained" exchange of gunfire followed, and Mr. Alexis was killed. Emmarie Huetteman contributed reporting.