If you are on federal probation and have a new state charge you need a lawyer who can actually represent you. You need advice but from soneone who has talkked to you, reviewed the file and otherwise prepared.
In general,there is no guarantee that the U.S. Probation Officer will find out that you were arrested. If you are asked directly or are obligated to disclose an arrest to your PO, you should be truthful.
However, if it is up to government channels, who knows how long it will take for the PO to learn. The officers who arrested you may not know of your federal status. Federal convictions and probation status are usually not included in a state rap sheet and local officers do not usually run an NCIC check as a routine matter. Obviously, every day that goes by, the computer networking in law enforcement becomes more sophisticated so, even without a direct NCIC check, it could show up.
Bottom line: consult a competent attorney who can look into it for you.
Your USPO likely will not know that you have been arrested on a state charge until he is notified by the state authorities, accesses your criminal history or is notified by you. A condition of your probation/supervised release is to notify your USPO if (among many other things) you have been arrested by state or local authorities. In my experience, unless you have been arrested for a minor offense (that did not require your being fingerprinted, and therefore, no record of the arrest is entered into a state or national database), there is no chance that your USPO will not discover the arrest. It is also my experience that the matter will be resolved much less favorably to you in the USPO discovers this arrest before you tell him or her.
-Joshua Sabert Lowther, Esq.
A person on federal probation who is arrested on state charges should make sure that his or her probation learns about the arrest as soon as possible. The conditions of probation require that the probationer notify the probationer officer when he or she has contact with law enforcement officers. It is also important that your attorney have both problems in mind when working on your case. It is often possible to coordinate the resolution of both charges to minimize possible jail time. In a case in which the probationer wants to make a plea deal on the state charge, it is important to make sure that any federal sentence for the violation run concurrent with the state charge. In most cases, the federal judge will not be willing to do that but the state judge will. In such a case, the federal case should go to sentencing first. An experienced criminal defense attorney should be able to handle this. Good luck.
THESE COMMENTS ARE NOT LEGAL ADVICE. They are provided for informational purposes only. Actual legal advice can only be provided after consultation by an attorney licensed in your jurisdiction. Answering this question does not create an attorney-client relationship or otherwise require further consultation.