BROOKLYN - A new report recommends that the Defense Department rethink how it protects its personnel and facilities.

The news comes following the Washington Navy Yard killings last September.

Former Navy Reservist Aaron Alexis gunned down 12 workers at the building before police killed him. Investigators say he had serious mental health issues that went unnoticed.

The report recommends greater limitations on security clearance and more routine background checks.

Last September, Alexis's mother spoke to the media from her Bed-Stuy home and said she was saddened by the tragedy, but glad he could no longer do harm to anyone.