The family of one of the victims in the Washington Navy Yard shooting filed a lawsuit Wednesday against two federal government agencies and two government contractors alleging that they failed to secure the Southeast D.C. facility and failed to respond appropriately to the myriad signs of mental health issues the shooter exhibited in the months and years before the massacre.

The 96-page complaint — filed in federal court in Florida on behalf of the family of Mary Frances DeLorenzo Knight — is the first lawsuit in the wake of the September shooting rampage carried out by a gunman who had an all-access security pass to the military installation. Knight, a computer scientist from Reston, was one of a dozen people gunned down by Aaron Alexis at the Navy Yard.

Knight’s family members had filed a claim last month essentially announcing their intention to sue the government; the suit itself, which names the Navy, the Department of Veterans Affairs and two government contractors as defendants, is the next step in the legal process. Like the claim, the suit is a detailed recitation of Alexis’s troubled past that Knight’s attorneys say should have served as ample warning.

Sidney L. Matthew, an attorney for the Knight family, said while the facts are detailed, the case itself is “simple.” The U.S. government and its various contractors should have noticed the many warning signs of Alexis’s instability before issuing him a security clearance. And failing that, they should have installed a metal detector at the Navy Yard to prevent someone from getting inside with a gun.

“It’s a simple negligence,” Matthew said.

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