8.4 Eth stolen by Dev…

I worked with a developer on an NFT project that sold fairly well. He was paid for his work.

2 months later, it appears he has taken the eth out of the wallet he had access to.

I'm waiting on a response from him. Assuming I don't get a response I will have to reach out to his references, contacts, and place of work, and tell them he has stolen 8.4 eth from a previous employer.

Does anyone here have any advice?

Here's where our eth is:https://etherscan.io/address/0x4012db7a18eff589370b17b727503042879deb37