Elkhart County Sheriff's Department Capt. James Bradberry says early indications suggest carbon monoxide poisoning was a factor in the deaths.
Relatives say Rider's father went to check the home when he couldn't get in touch with his son and found a car running in the garage. After calling 911, Rider's father collapsed but was taken to a local hospital when police arrived.
Officials haven't yet ruled on the couple's cause of death.