Here was a crime, the investigation is going on.
If you ask the blockchain.info was a BTC-address of his wallets, they would respond to it?
What are you asking? Do you want to know other addresses in his wallet? Use this:
https://www.walletexplorer.com/ Enter his address (the one you sent the money to) and it should show you if there are other addresses in teh same wallet.
You can always ask them it doesn't hurt, but I doubt they will do anything without a court order. FYI it's impossible to block an address. All they could do is suspend his blockchain.info account, but there's no way to take money from his address and send it back to you.