1968/36: The Mad Doctor of Blood Island 1968

 Trailer:

https://en.wikipedia.org/wiki/The_Mad_Doctor_of_Blood_Island

https://www.moriareviews.com/horror/mad-doctor-of-blood-island-1969.htm 

https://eofftvreview.wordpress.com/2020/08/08/the-mad-doctor-of-blood-island-1968/ 

http://1000misspenthours.com/reviews/reviewsh-m/maddoctorofbloodisland.htm