Where did Dancho Danchev go? The Bulgarian cybercrime researcher has been missing since last August. The only clues: A source who says he's "in a lot of trouble," and pictures of a mysterious government surveillance device found in his apartment.

Danchev is a "security consultant and cyber threats analyst," and a blogger for tech site ZDNet. His last post for that site was August 18th, 2010 and his colleagues have apparently been looking for him ever since. Over the past few months, they've called Danchev, reached out to Bulgarian authorities and even sent him snail mail when all else failed, according to a ZDNet blog post by Ryan Naraine. No response.

But they have turned up some troubling leads:

Last month, we finally got a mysterious message from a local source in Bulgaria that "Dancho's alive but he's in a lot of trouble." We were told that he's in the kind of trouble to keep him away from a computer and telephone, so it would be impossible to make contact with him.

ZDNet also posted an email Danchev sent to a friend on September 9th:

[Name redacted],

As I consider you as a trusted colleague, and someone who understands the big picture of cyber crime and cyber espionage, I'm attaching you photos of the "current situation in my bathroom", courtesy of Bulgarian Law enforcement+intell services who've been building a case trying to damage my reputation, for 1.5 years due to my clear pro-Western views+the fact that a few months ago, the FBI Attache in Sofia, Bulgaria recommended me as an expert to Bulgarian CERT -> clearly you can see how they say "You're Welcome".

Included were pictures of some sort of government surveillance device:

Very strange. Needless to say, if you have any information about Danchev's wearabouts, please let ZDnet (and us!) know.

Update: It appears that thing in the picture is a fairly innocent lighting transformer, though Danchev was clearly convinced it was something more malicious.

And some details about the timeline: Fellow security researcher Mikko Hypponen tells us that he saw Danchev at Interpol HQ in Lyon in early September and he was "fine." But by November, Hypponen and some colleagues had started wondering what happened to Danchev after not hearing from him for a while. These concerns were put to rest when security researcher Andre M. DiMino tweeted "I've heard from good sources he was well" on Dec 15th.

"I stopped worrying, until Ryan blogged about this again today," Hypponen told us.