But if you used Monero, they’d have a harder time proving what funds you may have access to.
The crimes in question involved real estate deals with paper trails. They also have transcripts of conversations where the partners acknowledge what they're doing is wrong and could potentially trigger an FBI investigation.
Monero won't save anyone from that.
The first part you can do with any cryptocurrency, the anonymity provided by Monero may allow you to succeed at the second.
FBI agent: What cryptocurrency assets do you own?
You: 2 BTC, 1 ETH.
FBI agent: We found some Monero transactions in your past, we think you're holding XMR and lying to an FBI agent about it. Off to jail for you.
They need evidence
>You: 2 BTC, 1 ETH.
bzzzt
You're supposed to remain silent, not expose yourself by lying.