This is heartbreaking. Plus, Due Diligence can only go so far.
In 2015, we had a company as a client. We did the due diligence before taking them and only accepted the work on payment in advance.
In short, never do anything until you have the money. No credit. If you had to work on credit, due every bit of due diligence you can, credit check everyone and check their history. We did all that and still got hit with one.
Then buckle up and prepare for the ride, as the court system is as good as useless.