Where can I find free whodunit-type game downloads like CSI that let you play for 1 hour? or even longer?

Prefer gently mysteries rather than encylopaedic but not too b. Not into overly complicated puzzles either. I'm a retired 60 yr old who loves murder mystery weekends and all of Agatha Christie books. Enjoy seeking out obscure clues but no ley lines or pendulums - I've done lots of those and find them tedious.