I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear about your brother's situation.
The first thing for your brother to do is contact the lawyer who was supposed to be handling the case for him and ask him to send proof of how the wife was served with notice of the divorce, because he's going to need that. If it was posted in the newspaper, he should get copies of that paper. That will help, but if she wasn't personally served with notice of the case, she may still be able to reopen things like alimony (it's not fraud, though, by any stretch of the imagination).
One way to prove whether someone is working is to get a copy of their tax returns. He can serve her with a Request for Production of Documents asking her to produce her tax returns during the time they've been separated. He can also ask her to produce her bank statements, which he can comb through for deposits and withdrawals. He can look at her credit card statements to see if she has a spending pattern consistent with someone who makes more than they're claiming. He can look at social media to see if any of her posts evidence a specific job, and to talk to her friends and family members. And if none of that yields any results, he could yield a private investigator to see what she does all day long.
A local attorney (in Florida) can also subpoena her bank statements if she won't produce them. They could also subpoena text messages from the cell phone company which potentially could give some insight into what she does all day long.
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