Laila Siddique was on her way to examine a patient at Penn State’s Hershey Medical Center when her phone began to tremble. The 25-year-old medical student glanced at the screen. It was a text from her father.

Nasir Siddique kept in close touch with his two children. He had come to the United States from Pakistan as a young man, enlisted in the Army and slowly risen through the ranks, working at the Pentagon and on Capitol Hill before retiring as a lieutenant colonel in 2010. He had traded the cigars and whiskey of his youth for a tightknit family, a large house in Bel Air, Maryland, and Friday prayers at a Baltimore mosque. And he’d recently landed a job as deputy environmental chief at Aberdeen Proving Ground, a century-old military base where he once served as a military officer.

At 57, with a military pension, the new job, a loving wife, and a son and daughter both studying to become doctors, Nasir Siddique had many reasons to be happy.

Instead, he was deeply disturbed.