Nicola Tesla--did he leave many mysteries?

I remember reading about a "death ray" that he had perfected but became clified by the Government supposedly yet the Government is still working on effective portable laser systems to knock down missles,etc. Were his papers "lost",are there any profound mysteries left unanswered, is there any validity to some of the more bazzar claims about his incomplete projects, the scope and depth of his knowledge that remains truely unexplained by believing scientists in this day and age or is it for the most part X-File type baloney?Please no websites-I get the impression many can't see the comic book from the truth.