CFAA doesn't apply here.

https://www.law.cornell.edu/uscode/text/18/1030

>(f) This section does not prohibit any lawfully authorized investigative, protective, or intelligence activity of a law enforcement agency of the United States, a State, or a political subdivision of a State, or of an intelligence agency of the United States.

So something can't be illegal for the police to do for the sole reason that it violates the CFAA. If it violates something else, I suppose CFAA charges can be added on, though.