Missing Head Movie - Help

[Donna]

To all B-Movie buffs out there...have you seen this one:
It's an old black and white movie, probably from the 50's, where an evil conquistador in California was put to death and his head severed from his body and buried separately...jump forward to the 1950 or 1960's...his evil minions find his head and hold it up to windows where his eyes glow and put anyone looking at them in a trance to do his bidding...it's a movie my family has not seen on late night since the 1970's but I would win HUGE points if I could find it to show them next time we get together...or, failing that, if I just knew the name of the movie...Any thoughts?  Thanks.

[J.R.]

The Thing That Wouldn't Die.

This movie was lampooned on MST3K, episode 805.