Just over a year ago, we broke the story of Silk Road, the underground online market that's like an eBay for illegal drugs. It's been thriving ever since. But as the summer drags on, Silk Road users are becoming increasingly paranoid over a series of unexplained disappearances. And the Drug Enforcement Agency has now revealed it's investigating the site. Is Silk Road really as invincible as it seems?

In early July, the DEA told the Austin TV news station KXAN that it was investigating Silk Road, where users openly buy and sell drugs, from heroin to ecstacy and pot. New York Senator Chuck Schumer had asked the DEA to look into the site after we first wrote about it about a year ago, but this is the first public acknowledgement that the DEA has heeded his call.

Silk Road users don't seem immediately concerned about news of the investigation. "ASSHOLE reporters writing lies," wrote user TrustusJones in a post about the article on Silk Road's bustling forums. He or she probably feels well-protected by the twin technologies Silk Road uses to keep users hidden: The anonymity software the Tor Network and Bitcoins, a nearly untraceable currency. (Proving its bona fides once again, Tor recently stymied an FBI kiddie porn investigation.)

But over the past few months, a number incidents have suggested that Silk Road users are vulnerable, unsettling some users and sparking rumors of a crackdown. Don your tin-foil hat, and follow me.

One of the most prominent incidents was the sudden disappearance of a much-beloved cocaine dealer named "MiN," in May. For months, MiN, who claimed to live in Canada, had sold and shipped some of the highest quality coke in the dark net—one user described it as "STRONG, euphoria and some speediness." After he vanished, customers flocked to the Silk Road forums to complain that their orders hadn't been filled. Rumors swirled that MiN had been busted and that he was actually the alter ego of a family of four from Ottawa who were arrested in mid-May and charged with exporting huge amounts of cocaine abroad. (The Ottawa Royal Canadian Mounted Police would not comment on whether Silk Road was involved in the Ottawa case.)

It was said that MiN tripped up by accepting Western Union money orders in addition to Bitcoins, which opened him up to being traced.

"If you ever did business with [MiN] then maybe you should stay on the down low for a month or two until everything blows over," wrote one user soon after his disappearance. If MiN actually had been busted, this could spell bad news for the dozens of Silk Road users he sent cocaine to.

Feeding rumors that something's amiss has been the unusual silence in recent days of Silk Road's anonymous administrator, who goes by the handle Dread Pirate Roberts. Given the technologies protecting it, the easiest way authorities could totally shut down Silk Road would be to infiltrate the board at its highest level: Possibly by pinching Dread Pirate Roberts himself. All members of the digital underground have painful memories of how the FBI turned the hacker Sabu, leader of the hacktivist gang LulzSec, against his foot soldiers. So they're always on the lookout for signs that "DPR," as his fans call him, might have been turned and is helping the authorities turn Silk Road into a giant honeypot.

What troubles especially paranoid Silk Road is that DPR is usually a voluble presence on board. In honor of 4/20, he held a massive drug sale on Silk Road, which was advertised as including a giveaway with a grand prize of "a trip for two with all the trimmings to paradise, all expenses included." But he's only posted on Silk Road forums three times since May 6th.

"Does anyone else find it strange that DPR's post count dropped significantly?" asked a user today. "I never payed much attention to it before until a friend mentioned that some major MDMA distributors from the NW USA heard about the operators of [Silk Road] getting caught. I brushed it off as a rumor until I looked through DPR's post count and now I'm a bit concerned. I know this is pure speculation as I have no evidence or reliable source, It just seems like something worthy of discussing."

The mood hasn't been helped by news reports that show authorities around the world are increasingly looking into Silk Road. Earlier this month, a New Zealand customs officer arrested on Methamphetamine charges was found to be a member of the Silk Road. This summer Australia has recently experienced something of a delayed Silk Road craze, with every major news outlet sounding the alarm about the mail-order drugs supposedly flooding into the country from the site.

In a forum post last week, a longtime user named mr_sketchy captured the sense of unease some Silk Road users have been feeling in recent days. "Why are all the top Vendors disappearing?" he asked. "I know a few got busted and the nature of this site is that people on here are rather transient from even the very early days. Perhaps its my imagination but is it me or is the rate of which the bigger and top quality vendors disappearing increased in the last few months?"

Almost every conspiracy theory on Silk Road ends with a similar qualification: "Perhaps it's my imagination... It's probably nothing... I'm probably just being paranoid..."

And these lateset ripples probably are just another wave of unfounded paranoia that sweeps periodically through this dark corner of the web, fueled by the mind-bending substances traded there and the anonymity that makes the whole thing possible. Maybe MiN disappeared because he was a scammer, and the other vendors just got sick of dealing mail-order drugs. Maybe Dread Pirate Roberts is on vacation with the winner of his 4/20 contest. Or maybe it's something else.