If you are close friends, why not just sit down and ask him? Tell him that it seems as though he looks at you differently, and if so, you're interested.
The best way would be to just come out and ask him. It might be a bit awkward, but in relationships such as these it can be impossible to tell otherwise.
In this situation the best thing to do is ask. You both have to be on the same page about your feelings toward each other so that no one gets hurt. This will save your friendship if incase the feelings aren't mutual.
