Mr. Reiner, who was arrested in connection with the deaths of Rob and Michele Reiner, once estimated he had been in drug treatment 18 times as a teenager.
Nick Reiner, who is in custody but has not been charged with a crime, has openly discussed his battles with heroin and cocaine in interviews and podcasts.
Mr. Reiner, who was in “All in the Family,” directed films including “This Is Spinal Tap,” “When Harry Met Sally …,” “The Princess Bride” and “A Few Good Men.”