Los Angeles Times:

Federal agents seized a cellphone belonging to a prominent Republican senator on Wednesday night as part of the Justice Department’s investigation into controversial stock trades he made as the novel coronavirus first struck the U.S., a law enforcement official said.

And:

The seizure represents a significant escalation in the investigation into whether Burr violated a law preventing members of Congress from trading on insider information they have gleaned from their official work.

On the Apple side:

A second law enforcement official said FBI agents served a warrant in recent days on Apple to obtain information from Burr’s iCloud account and said agents used data obtained from the California-based company as part of the evidence used to obtain the warrant for the senator’s phone.

I’m curious what part of Burr’s iCloud account the FBI got access to. Was it iCloud Drive? Was it iCloud backup (perhaps Burr’s backup was not set to be encrypted)?

From Apple’s iCloud security overview:

iCloud secures your information by encrypting it when it’s in transit, storing it in iCloud in an encrypted format, and using secure tokens for authentication. For certain sensitive information, Apple uses end-to-end encryption. This means that only you can access your information, and only on devices where you’re signed into iCloud. No one else, not even Apple, can access end-to-end encrypted information.

For a clue on what information might have been available to the FBI, take a look at Section III of Apple’s Legal Process Guidelines (H/T Mike Wuerthele, AppleInsider).

Bit of a rabbit hole there, but an interesting read. Seems clear the FBI got what they needed.