Hackman "butterfly" knife, Vietnam related?

[digi-shots]

I've read a little bit about these knives and I don't know if anyone has come to a conclusion or not as to their use in Vietnam. There's talk that they may have been used by the CIA and/or MACV. I've seen them with both red and black plastic handles. Most posts and info that I've read were a few years old and nothing new on them lately.

 

Here's one I recently got... very similar to others I've seen listed. This one has the Hackman name & logo on both sides of one handle, and nothing on the other handle. I've seen different styles of name stamping on the handles... I don't know if this helps date the knife or not.

 

If anyone has any similar ones, please feel free to post your pics.

 

Thanks for looking!