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I am sorry to hear about your situation. If you were no longer on probation when this incident occurred, then you do not need to contact your old PO.
If you were/are still on probation, then you would need to contact your PO. However, chances are that the PO will learn of the arrest anyhow. At this point, one may wish to "smooth things over" with the PO to ensure that they do not "violate" you for violation of any probation terms such as being violent, etc.
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