For 23 years, she lived in the shadow of a question. In her waking hours, she turned to God and Montgomery County detectives. In her sleep, she looked for her mother.

“Mama,” Lauren Preer would say. “We need to find out what happened.”

Then another day would go by without Leslie J. Preer, or answers. So she carried on — living with the fact that her mother, then 50, had been beaten to death in an upstairs bedroom of her home in Chevy Chase, Md.