FBI agents used Instagram posts of the burned cars, along with 500 photos from various photographers, to identify the wording on the woman's shirt: 'KEEP THE IMMIGRANTS, DEPORT THE RACISTS,' the FBI agent explained in his affidavit, VICE reports.
Agents discovered that the shirt was custom made and sold on Etsy and found that a user - Xx Mv - had posted a review about purchasing the shirt. The URL belonging to the Etsy was 'alleycatlore.' The page listed Philadelphia as being where the user lived.
The FBI then Googled 'alleycatlore' and found a user named 'Lore-Elisabeth' on Poshmark. Agents then looked up 'Lore-Elisabeth Philadelphia' and found a LinkedIN page for a woman who works as a massage therapist for a company in the Philadelphia area.
Authorities then used videos from the company's Vimeo account to identify tattoos that matched Blumenthal to the woman at the protests.
Authorities found a phone number on the website and then used it to identity the woman's address and DMV photo.
While this occurred, Etsy provided purchasing records - following a subpoena - and confirmed that Xx Mv purchased a shirt. The subpoena also revealed that the items were sent to a Lore Elisabeth in Philadelphia.