Never heard of that. But about Foster's car: there were items found in it and inventoried by the Park Police, which clearly never belonged to anyone in the Foster family nor anyone they might have been friendly with.
This implies that a stranger or strangers were in the car, likely right before it was found in the Ft. Marcy lot. Likelihood is that those who left the items in Foster's car had driven the car to the parking lot after the victim was dead in order to fake the "suicide," then forgot to retrieve their items or were so hurried to leave the park that they had to no choice but to leave these potentially valuable clues in place.
My favorite cover story for “miscellaneous items left behind at the scene of a crime” is, NO CRIMINAL WOULD BE THAT STUPID. To counter that argument especially for young folks, “watch the Maury Povic show.” People will take a lie detector for millions to watch, while a DNA test is being run to see if they ARE the Father, and whether or not they have cheated with their girlfriends mother.