He was unassuming, sweet, and friendly. “Saved” in church as a teen, he never caused trouble. In the Navy, they called him Opie. Though he was a big guy, he had a soft, boyish demeanor. “The boy next door,” said those who worked with and knew him.

But John Eric Armstrong had a dark secret—hidden even from those closest to him.

Prowling Detroit’s well-known pocket of prostitution on historic Michigan Ave, this young husband and father picked up unsuspecting women who thought they were simply meeting a john. He seemed innocent, even driving a Jeep with a front plate reading “Baby Doll.” But they soon discovered, he could turn on a dime — fly into a rage. Sometimes he would leave his victims alive, but sometimes he didn’t.