A man in Glen Ellyn, Illinois, has been taken into federal custody for making threats on Facebook to shoot a “high net-worth individual” before leaving for Pakistan.

Mohammad Waqas Khan, who worked as an Uber driver in the Chicago suburb, was arrested in May for violating conceal and carry laws, and was still incarcerated this month when he was hit with the federal charges. Authorities said Khan bought a round-trip ticket to Pakistan in April, and that they had been following him and observing his social media posts before arresting him.

Khan, who prosecutors say may have mental health issues, made many violent threats on the site, including against Chicago mayor Rahm Emanuel and an alderman. His defense says he was simply ranting online or posting rap lyrics, but a judge noted “there is nothing rap-ish in anything he posted.”

“Now I’m gona get my revenge, and that involves putting bullets in someone’s body, so get out of the way or I’ll literally shoot at them as well and we’ll end up with a much bigger scenario on our hands,” one of Khan’s posts said. “I’m not leaving America without getting revenge even if it costs me my life.”

Though this is an extreme case, it’s always good to remember that the things you post on Facebook can be held against you—even in a court of law.