The account told its SimpleX group the app was "100% anonymous".

The FBI says it unmasked him anyway, using Reddit and Amazon records, a stakeout and a paid informant.

Agents seized his rifle and about 190 rounds from his Pennsylvania hotel room and bags on 12 September.

He hid behind the name "Hamza Al Rashid" on SimpleX, a messenger that needs no phone number or email.

Separately, Discord flagged "alternate" accounts that shared IP addresses or browser cookies with Kramer's known accounts.

One of them, last used from his home internet connection, sent users to a Discord profile showing a masked man in front of the ISIS flag.

Hamza Al Rashid had also called SimpleX "the most secure messenger available".

Weeks later, a Reddit account registered to Kramer's email wrote "simplex is where its at".

Hamza Al Rashid offered to chat at "7PM mecca time", noon in Pennsylvania, which the FBI says fits Kramer's night shifts.

Agents watched Kramer being driven to work at 9:41PM and home at 6:31AM.

The paid informant chatted with Hamza Al Rashid, who laid out a plan to blind a crowd with pepper grenades.

Amazon records show Kramer had bought pepper spray.

A federal grand jury indicted him on 6 October for receiving the rifle to commit terrorism for ISIS.

He has pleaded not guilty.

Source: Legal Document.

Spotted by International Cyber Digest.

Guess a secure messenger won't protect you from your own opsec ignorance, huh?

That's one possibility. The other is that they found an exploit for SimpleX and used parallel construction to avoid disclosing it.