Vampire movie in Mitchell Caverns, CA?

[Bob]

Ok, movie fans, this one's eluded me for 20 years. In the 1970's (or maybe late 1960's?) a vampire movie was filmed in Mitchell Caverns State Park, CA, near old Hwy 66 (now Hwy 40). I have no title, director, "stars", etc.

Does anyone have a clue what this movie could be? I'd love to buy a copy if I can find it.

[John]

Do you have anything more to go on, like specific scenes?