Senate committee investigating prison after empty guard towers allowed carjacker to escape. In a maximum security federal prison in California, convicted carjacker Guaymar Cabrera Hernandez made a run for it. A key to his brazen escape last month: Five guard towers ringing the perimeter of the compound were not staffed. Turns out, they have been empty for nearly six years. The breach has now drawn the scrutiny of the Senate Homeland Security Committee, which is exploring the increased reliance on fencing technology at the nation's most secure prison facilities - in lieu of tower officers who once represented the last line of defense against escape and other disturbances. Ref. USAToday.