Company Vetted Aaron Alexis And Edward Snowden

CHRIS LAWRENCE IS "OUTFRONT" WITH THIS INVESTIGATION. >> Reporter: ED SNOWDEN, AARON ALEXIS. ONE THING IN COMMON. THEY WERE BOTH VETTED BY THIS COMPANY. IN FACT, USIS PERFORMS MORE THAN HALF THE GOVERNMENT'S CHECKS. >> THE PROBLEM IS THEY'RE DOING SO MANY BACKGROUND INVESTIGATIONS THAT THEY HAVE A LOT OF YOUNG PEOPLE WHO WORK FOR THEM. >> THE ATTORNEY DOES A LOT OF WORK INTELLIGENCE OFFICIALS, REPRESENTING THEM IN THE CLEARANCE PROCESS. WHILE USIS OUT THES ITS HIGHLY EXPERIENCED TEAM DOING IN DEPTH INVESTIGATIONS, HE SAID THE INVESTIGATORS HE'S DEALING WITH HAVE VIRTUALLY NO MILITARY OR INTELLIGENCE BACKGROUND. UNLIKE THE FORM HE FBI AGENTS WHO USED TO DO THE WORK. >> THEY WERE A STATE TROOPER FOR 20 PLUS YEARS. THEY HAD KNOWLEDGE OF THE PROCESS. THEY KNOW WHAT THE GOVERNMENT WAS LOOKING FOR. THEY KNEW WHAT QUESTIONS TO ASK. >> THAT WAS BEFORE THE NUMBER OF AMERICANS HOLDING CLEARANCES BALLOONED TO 5 MILLION. BUT THE ISSUES DON'T REST WITH CONTRACTORS ALONE. THE NAVY WAS AWARE ALEXIS SHOT UP SOMEONE'S TIRES IN 2004 AND THEY MADE THE CALL TO STILL GIVE HIM A CLEARANCE. WHEN ALEXIS COULD KEEP FOR TEN YEARS. >> WOULD SHOOTING UP SOMEONE'S TIRES BE ENOUGH TO BAR HIM FROM A SECURITY CLEARANCE? >> THERE ARE CERTAIN CRIMINAL OFFENSE THAT'S CERTAINLY WOULD GIVE US PAUSE BEFORE WE GRANT A SECURITY CLEARANCE. WE DON'T KNOW ENOUGH ABOUT WHAT WE KNEW IN 2007 TO COMPLETELY ANSWER THAT QUESTION RIGHT NOW. >> AFTER ALEXIS GOT HIS CLEARANCE, RHODE ISLAND POLICE ALERTED THE NAVAL STATION AFTER AN INCIDENT WHERE ALEXIS TOLD POLICE HE WAS HALLUCINATING AND HEARING VOICES. BUT NAVY OFFICIALS INDICATE IT WAS NEVER RED-FLAGGED. >> WHAT SPECIFICALLY SHOULD HAVE HAPPENED? >> ONCE THAT REPORT CAME IN, HIS LOCAL BASE ACCESS COULD HAVE BEEN SUSPENDED. AND LIKELY SHOULD HAVE BEEN. THEN THAT INFORMATION WOULD HAVE FILTERED OVER TO THE CLEARANCE