The FBI used social media to track down a masked Philadelphia protester who allegedly lit a police car on fire during a May 30 protest. Agents tracked Lore-Elisabeth Blumenthal starting with photos of the moment she allegedly set the car on fire that were posted to Instagram. The photos led agents to the Etsy shop where the shirt she wore could be purchased, then to her LinkedIn page, then to her Poshmark profile, then to Blumenthal herself. Blumenthal has been charged in the incident and now faces up to 10 years in prison. Civil-rights advocates are now raising red flags, saying the extent to which law enforcement agencies can use social media to surveil anyone online is concerning. “Social media has fueled much of the protests and has also become a fertile ground for government surveillance,” said Paul Hetznecker, who has organized lawyers to represent protesters, including Blumenthal. “I think people have lost awareness of that.”