James Handy was in dozens of films and TV shows over his decades-long career ... and he was committed to one more project before he was brutally slain this week at his girlfriend's home ... but it sounds like fans will never see his last work. Heidi Anderson-Swan , writer and producer of the film "Kickback, V" tells TMZ ... James was one of the sweetest people she's met in Hollywood -- he helped her a few times on projects when she was breaking into the industry -- and she had to have him in