I am to trying to identify a murder mystery film, possibly from the 1970's. The setting is a large house (mansion?) near water, possibly an island. A group of people are picked off one at a time, (agatha christie style). When the murders take place, all that is shown of the killer is the hands in black leather gloves. It is revealed that the killer is a rather anemic looking, blonde girl of about 14 years of age. Thank you.

Red herring? Ten little indians? not the original The Haunting is it perhaps?

April Fool's Day?

I've never seen the movie, but it sounds a little like the book "And then there were none" (Which I believe was also titled as "Ten little Indians", as said by virgoguy)

Try 'Legacy'