https://theintercept.com/2021/02/22/capitol-riot-fbi-cellphone-records/

WITHIN HOURS OF the storming of the Capitol on January 6, the FBI began securing thousands of phone and electronic records connected to people at the scene of the rioting — including some related to members of Congress, raising potentially thorny legal questions.

Using special emergency powers and other measures, the FBI has collected reams of private cellphone data and communications that go beyond the videos that rioters shared widely on social media, according to two sources with knowledge of the collection effort.