On Sunday, a North Carolina man named Garrett Grimsley made a public post on Whisper that sounded an awful lot like a threat. "Salam, some of you are alright,” the message read, “don't go to [Raleigh suburb] Cary tomorrow.”

When one user asked for more information, Grimsley (who is white) responded with more Islamic terms. “For too long the the kuffar have spit in our faces and trampled our rights,” he wrote. “This cannot continue. I cannot speak of anything. Say your dua, sleep, and watch the news tomorrow.”

Within 24 hours, Grimsley was in jail. Tipped off by the user who responded, police ordered Whisper to hand over all IP addresses linked to the account. When the company complied, the IP address led them to Time Warner, Grimsley’s ISP, which then provided Grimsley’s address.

It’s unclear whether Grimsley had any intention of carrying out the attack, although police found significant weaponry at his home, including an AK-47 and 340 rounds of ammunition. It’s unclear whether the weapon was legally owned.

Investigators also gained access to Grimsley’s Facebook account, including his private messages. Many seem to indicate the comments were made in a trolling spirit. “I yell about jihad and shooting all the people all the time, too much CSGO [likely reference to Counter Strike Global Offensive video game] and nasheeds [Islamic videos with speeches and music in the background],” one message reads. “The FBI will understand I was only reading Dabiq for the pictures, right?” (The affidavit notes that Dabiq is an online magazine published by ISIS.)

After Grimsley became aware of the FBI response, the messages grew more tense. "Holy fuck I'm actually going to get raided,” he wrote to a friend. He attempted to encrypt his hard drive to protect it from police, but ran out of time; the process was 63 percent complete when agents obtained the laptop.

Whisper came to prominence in 2014, promising users a way to post messages anonymously, but has since drawn fire for maintaining too much information on its users. In this case, Grimsley’s IP address was accessible to the company, and could be requested by law enforcement.

Because Whisper’s servers are located outside of North Carolina, Grimsley has been charged with transmitting a threat over interstate commerce, a federal crime punishable by up to five years in prison.