Block on Trump's Asylum Ban Upheld by Supreme Court
Feds do not care if on "anonymous" apps you made it -- a threat to kill will get you raided.
Whisper Sweet Somethings
Garrett Grimsley may have thought his communications were private, having made them on a supposedly anonymous messaging app, Whisper. Grimsley, a resident of Cary, North Carolina, wrote to another user:
"Salam, some of you are alright ... don't go to Cary tomorrow ... For too long the kuffar have spit in our faces and trampled our rights ... This cannot continue. I cannot speak of anything. Say your dua, sleep, and watch the news tomorrow."
Then again, Grimsley might've known the messages weren't completely protected: stories of Whisper monitoring users have been around for years, and he later joked on Facebook that he expected to get "raided." And that's exactly what happened.
Hours after making the threats, FBI agents arrested Grimsley and seized his (only partially) encrypted computer along with an AK-47 and 340 rounds of ammunition. According to the criminal complaint against Grimsley (via Ars Technica):
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 f**k I'm actually going to get raided."
Not So Anonymous
How did feds make it to Grimsley's doorstep so quickly? With the help of a cooperating witness (CW), most likely the other participant in Grimsley's Whisper chat. Ars Technica's Cyrus Farivar walks it through:
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.
So, to recap: threats to do harm are illegal, no matter where you make them; and you're never as anonymous on the internet as you think you are.