When Nick Reiner was photographed alongside his family at the Los Angeles premiere of his father’s comedy musical, “Spinal Tap II,” in September, he wasn’t smiling. Instead, the son of legendary Hollywood director Rob Reiner and producer Michele Singer Reiner stood impassively for the family portrait alongside his siblings.

Prosecutors in Los Angeles were weighing possible criminal charges on Tuesday for the son of Hollywood actor-director and political activist Rob Reiner and his wife Michele, who were found slain in th...

Nick Reiner, who has publicly acknowledged a struggle with drug addiction, was arrested that night near a downtown Los Angeles park close to the University of Southern California campus.