The shooter at the Washington Navy Yard had a "pattern of misconduct" as a Navy reservist, had sporadic run-ins with the law, and had contacted two Veterans Administration hospitals for apparent psychological issues, sources have told CNN.

Somehow, none of that prevented Aaron Alexis from getting clearance to the Washington Navy Yard as a subcontractor.

In the wake of the horrific incident that left 12 victims and the gunman dead, lawmakers and military experts are calling out the vetting process for contractors and subcontractors. Did the military even know the things about Alexis that news agencies managed to find out within hours?

Sen. Susan Collins, a Republican who serves on the Intelligence Committee, said she now questions "the kind of vetting contractors do."