Tax preparer fraud situation, need some advice
So recently, I onboarded a new client. Originally I was only going to file delinquent California LLC filings. Anyway, he uploaded copies of his 1040s and fraudulent deductions were taken resulting in a significant understatement - a paid "preparer" filed this return. I brought it to the attention of the taxpayer, he was shocked and wants to voluntarily fix it.
I told him for now, do not confront him. I was helping him fill out the preparer misconduct affidavit and asked him where he heard about this preparer, he told me through a trusted co-worker who referred him.
Anyway, my concern is, the co-worker and potentially other people in the taxpayers personal circle are being preyed on by this person and it's only a matter of time until the IRS or FTB catches on. If they are also victims, they should know so they can take action. However, I have a what-if bothering me, what-if the co-worker is working or tips off the preparer.
What is the best way to handle the situation with the co-worker? Would it be unwise for him to inform his co-worker?
Based off my understanding of circular 230, my obligation is to my client. Still, there is nothing stopping him personally from bringing it up to his co-worker.