The Man Who Turned To Stone (1957)

Starring Victor Jory, William Hudson, Charlotte Austin, Jean Willes, Ann Doran
Directed by Leslie Kardos
(actor & director credits courtesy IMDB.com)

A social worker at a women's detention center learns the center's staff is performing deadly experiments on the inmates and covering them up as natural deaths. 

One of producer Sam Katzman's several 1950s science fiction pictures for Columbia, I've been rather fond of this film since I first saw it several years ago on a Goodtimes VHS tape.  Katzman was known for cheap productions, and although this science fiction film lacks any real special effects, Kardos directs effectively, making the most of some limited makeup and a quality cast to drive the story forward.  Jory, as the center's director, is wonderfully creepy while masking his crimes under a benevolent appearance, Austin is believable as the one member of the staff who wants to help the women under their charge, and the always welcome Paul Cavanagh adds gravitas and believability to the revelation of the staff's shocking secrets.  It's an entertaining chiller and one that's well-paced and fun to watch.