Who is Paul Whelan, the Marine veteran left behind in Russia in the Griner-Bout prisoner swap?

I thought Bergdahl was a crappy trade, she was caught red handed with drugs the Marine and schoolteacher have done nothing wrong.

I would rather have our Marine back

A Marine with a BCD or an America hating celebrity. Quite the pair, but Americans both. The story is not so much them, as yet another lopsided Bergdal style swap. AND, NBC's rapidly withdrawn reporting that the administration had a choice but devolved into identity politics -again - is another admin/media scandal.