I just finished Joseph Cox's book Dark Wire.

According to the book law enforcement intervened in the vast majority of cases where someone's life was in danger. There was only one case mentioned in the book where they were unable to intervene.

ANOM was run by the FBI's office in San Diego, CA. What is interesting to note is that the intelligence gathered via ANOM was, in almost all cases, provided to and used by law enforcement outside the United States.

There are no limitations on US law enforcement and intelligence agencies gathering information on people who are not "US persons" (broadly non-US citizens living outside the US). Presidential Order 12333 currently (who knows about the future) prohibits collecting information on "US persons" without a court order. The interception that are covered by a court order must be targeted to individuals where there is probably cause to believe that they are committing a crime. Steps must be taken to limit the amount of collateral information collected on "US persons".

Although FBI investigators attempted to get warrants for the ANOM collection on "US persons" they failed in almost all cases. Apparently FBI higher-ups where nervous about the scope of ANOM and didn't support pursuing warrants. So ANOM was largely used by countries outside the US.