Worried my dad has fallen for a whatsapp investment scam

My dad was contacted through WhatsApp by a group called Doppler Investments. He has been trading with this group for almost 2 months he has lost money and made money. But he has not really transferred off the exchange. They are having him use an exchange called XUSCoins and he is trading cryptos like STE, AAVE, BGV, NEC. He was able to transfer some money off the platform once but it was only $75 about a month ago. I just had him initiate another withdrawal to his trezor but it has not shown up yet. It was USDT or ERC-20 so I don’t know how long that would typically take to show up. He is convinced this is all legitimate but I am really concerned. He has 50k on the platform right now. Are there any telltale signs I should have him look out for to see if this is legitimate?

Update* It seems that he most likely has been scammed. Please be nice my dad is 65 and has stage IV cancer that may be impacting his cognitive function. Can someone ELI5 exactly what steps he should take now to report this? Would there be any use in trying to play along with the scammer to get any other information?

Second Update His withdrawal went through! He was able to get $1000 of it out. Should he messages the scammers first before trying to make a larger withdrawal saying he needs to the money to take out a larger loan? Or should he just try to withdraw without saying anything?

Third Update He tried telling the scammer that he was going to obtain a loan from crypto.com and needed to withdraw some to use as collateral so that he could double the amount he had on the platform. He initiated a 25k USDT withdrawal and they sent him an email asking for ID verification. I obviously told him not to send his ID. He then tried making several other small withdrawals and they were all rejected right away. Today he messaged another one of the head scammers in the group (although all these group members are probably the same person) and said he was going to be selling an investment property and planned to add in 400k but he just needed to be sure he could withdraw first. He then converted all the USDT to BTC and attempted to withdraw it and that currently still says pending. We obviously don’t have high hopes but it was worth a shot. He has filled out reports on iC3.gov, USA.gov, and report fraud.ftc.gov. We’re not really too sure if there’s any other law enforcement we should contact or if we should contact the exchanges the fraudsters are using before working with law enforcement. My dad considers the money lost at this point and has learned a valuable lesson. He seems to be handling it pretty well or at least acts that way around me.

Please educate your families about these types of scams. To the people that frequent, this sub I know it seems like common sense but there are many people who don’t know crypto or spend a lot of time online and aren’t seeing these types of things and can be easily fooled

Scammer’s address for those curious 0xc43db4af6647ea9428f8215bfac3bde1dbd0b98e

He also sent money to a BTC wallet but he hasn’t sent that one to me. I’ll post it if he does