[pvarangot]

The police can't ask for your cellphone while you are in the limbo of being detained but not arrested. Once you are arrested they can get a warrant for your cellphone, but getting it unlocked can be a whole different issue. If you are arrested they will usually identify you via face recognition or fingerprints.

[cortesoft]

I think they would have been able to arrest everyone inside the Capitol building, since everyone inside was breaking the law.

[pvarangot]

Yes most definitely. They also have the infrastructure to do so, but not sure they have the infrastructure to keep them arrested until everything is sorted out.

[vkou]

They absolutely have that infrastructure. Handcuff all of them, and let them lie face-down on the pavement while you process them.

That's what usually happens with mass arrests.

[elorant]

I don't think parent comment was about confiscating phones rather than identifying which phones were in the area during the infiltration. If you can sort out the ones who had reason for being there, everyone else is a possible culprit.

[pvarangot]

Legally getting that information from cellphone towers or tech companies and then acting on it would take at least one week, even if they had killed multiple people. A three letter agency could probably get it clandestinely and act para-legally for example putting people on surveillance or getting a flash arrest warrant for an unrelated but quickly to parallel-construct crime, but I don't see that happening in this case.

If there's going to be arrests based on cellphone tower or mobile app data I would expect them to happen by the end of next week.