Notice in the TV movie "The Night Stalker" (1972) when the refrigerator containing blood is opened there's blood labeled "Benjamin Richards". Obviously a left over prop.
Series star Christopher George, whose character supposedly had a medical/genetic condition that made him immortal, died of a heart attack aged only 52, barely a decade after the series ended.
It's been pointed out that Christopher George died of a heart attack at an early age. This was reportedly due to damage to the organ from a Jeep roll-over accident while he was filming "The Rat Patrol" a few years before this series.
The series was based on the 1962 science fiction novel "The Immortals", by author James E. Gunn.