I suspect they have direct evidence that this developer coordinated specifically with criminals to help guide them on how to use the system for money laundering.
This would be similar to the developer of the encrypted phones that everyone defended initially until it became known that he flew to other countries to train drug dealers how to use the phones.
In this crypto business, it is not enough to just build the system and expect people to magically know that it's for them and how to use it - 50% of the work is selling and training people on the system.
This is all speculation based on previous similar cases.
This would be similar to the developer of the encrypted phones that everyone defended initially until it became known that he flew to other countries to train drug dealers how to use the phones.
In this crypto business, it is not enough to just build the system and expect people to magically know that it's for them and how to use it - 50% of the work is selling and training people on the system.
This is all speculation based on previous similar cases.