The mystery surrounding noted security researcher and blogger Dancho Danchev continued on Monday, after reports from Bulgaria suggested that Danchev may be confined to a hospital in the country.

The unconfirmed report comes by way of Dnevnik.org, a Bulgarian online publication, which cites two unnamed sources as confirming that Danchev has been hospitalized since December 11, 2010. Danchev is now "stabalized and will soon be discharged," Dnevnik reports. The report did not say why Danchev had been hospitalized.

Threatpost reported on Friday that Danchev, a frequent blogger on computer security for ZDNet.com's Zero Day blog, has been missing since early September. Regular posts to his personal blog and Zero Day ceased. During that time, he has been offline and unreachable by phone or e-mail, though he appears to have been using Twitter through late October.

In recent days, disturbing e-mail messages have surfaced that suggested Danchev might have run afoul of law enforcement or intelligence services in Bulgaria, including an insurance e-mail Danchev mailed to friends that claimed he was being set up by the police for his "pro Western" views.

The U.S. Embassy in Sofia is looking into Danchev's disappearance and said it sounded "strange," but had nothing to report as of Monday, according to press attache Vince Campos.

Danchev is an expert on the functioning of cyber crime networks and carried out extensive research into the operations of the online gangs behind malware like Koobface and Zeus. His last post, dated September 11, 2010, summarized three years of posts on cyber jihad operations online. Those posts earned Danchev enemies online, but communications from the researcher suggests that it was the authorities in Bulgaria, rather than miffed cyber criminals, who were out to get him. An e-mail sent to confidants to be published in case of an emergency names a local police inspector in Bulgaria as the force behind an 18 month long effort to frame him for his pro Western views.