Buddy Ebsen was 64 years old when the show started.
Barnaby is renowned for his scientific ability. However he has a habit demonstrated several times of blowing into the evidence bags to open them up. This would contaminate anything he put in the bag.
During original broadcast run, the opening credits would follow the setup scene. Therefore the first victim was not listed among the guest stars since their character is already dead. Only in Barnaby Jones: Deadline for Murder (1980) was initial victim, Alex Henteloff, included in the opening credits.