Legal Question in Criminal Law in California

If you think your daughter is the victim of a crime, tell the police. The authorities will subpoena her records if they believe the case is worth pursuing.

You cannot subpoena records on your own unless you file a civil lawsuit, perhaps in the form of a petition for a restraining order, against the person you say is a predator. But you should expect Verizon -- and your daughter -- to oppose the subpoena. You will have an uphill battle persuading a court to let you have the records, but if your evidence is strong the court may go along with your request.

One final note: You haven't said how old your daughter is. My answer thus far has presumed she is a minor. If she is 18 or older, she is an adult and is entitled to make her own decisions. The courts and the prosecutors will not intervene if she doesn't want them to. That her phone is on your account is not nearly enough to overcome her rights.