If we’ve said it once, we’ve said it 1,000 times: these so-called "anonymous" messaging apps simply aren’t anonymous. To put it another way, if you’re dumb enough to make violent threats on them, you’ll get caught

According to a newly released federal criminal complaint, Garrett Grimsley of Cary, North Carolina, allegedly used the Whisper app to make such remarks on February 19. Hours later, local police and the FBI arrived at his door to search his apartment.

As per an FBI affidavit, Grimsley (under the name "Spark_Pure") wrote in a public post: "Salam, some of you are alright, don't go to Cary tomorrow." Another Whisper user, who was not named in the affidavit but is referred to as an unnamed "cooperating witness (CW)," responded: "Why—what's happening in Cary tomorrow?"

The two then engaged in a private chat during which Grimsley said: "Aslam alaikum brother. For too long the kuffar have spit in our faces and trampled our rights. This cannot continue. I cannot speak of anything. It will be only the beginning, insha’Allah."

Presumably, the CW then informed federal and/or local police, who contacted Whisper. The company, as per its stated policy , says that it will comply with law enforcement requests for user data. That same policy says that the company does not retain any real name, address, or other kinds of personal information about its users but "may retain for a limited time certain IP addresses associated with a device that accessed Whisper." (The company did not respond to Ars’ request for comment.)

Whisper then handed over the IP logs to authorities, who then contacted the relevant providers including T-Mobile and Time Warner Cable. Those companies seemingly provided billing information for one Garrett Grimsley, including his home address.

When law enforcement arrived at his door, Grimsley was in the middle of a chat with another Facebook user named "Tim Tam." As the affidavit continued:

The Facebook private messages between "Grimsley" and "Tim Tam" revealed a lengthy conversation indicating that they were both aware of the Whisper posts and that they were both expecting "Grimsley" to get "raided" by law enforcement. At one point, "Tim Tam" stated "we're going to be on CNN tomorrow god damnit" and later "I swear to god you're going to get a swat team". In an apparent reference to "Grimsley" spotting a law enforcement surveillance vehicle, "Grimsley" told "Tim Tam", "holy fuck I'm actually going to get raided."

Tim Tam also did not respond to Ars' request for comment.

According to the same affidavit, Grimsley refused to speak to law enforcement, but he had been attempting to encrypt his computer’s drive when they arrived—it was only 63 percent done. (Presumably both his phone and computer were seized.) Agents found an AK-47 with approximately 340 rounds.

He was charged with one count of "transmitting a threat in interstate commerce to injure the person of another." Grimsley, who remains in federal custody, is set to appear again before a federal judge in Raleigh, North Carolina, on February 24.