Herbert William Mullin was an American serial killer born on April 18, 1947 who operated in Santa Cruz, CA. 
Mullin was serving life in prison for 13 murders which he says he committed to prevent further natural disasters.  Mullin died of natural causes on August 18, 2022.

3 1/2" x 4 3/4" photo printed on typing paper with an original signature on the back.
Hand signed, Herbert Wm. Mullin.
 
Mullin signed photos are rare.