Anyone know what this is or where its from?

My neighbor brought this to me yesterday asking if there was anything i could find out about it. He said he isnt sure if it was his dads or his dads dads. Anyway its a really solid knife and ive never seen anything like it before, it has a sheath that folds out that the blade folds into. When your not using the sheath it doubles as a means to lock the blade in position so the only way to close the knife is to unfold the sheath from the handle. There is nothing as far as stamps or names or any markings on the knife so i have no idea what it is??

That is what is referred to as folding bowie or folding hunter. Style came around early to mid 19th century. Was copied a lot.
Try looking in knife forms and you could possibly find more information there.

V/R
Tim