"When the police got the search warrant, they managed to find the private keys" - I wonder where they kept their keys?
Were the keys in Heather's makeup bag? (ironic)
It was kept on the cloud, and the DOJ was able to crack the password and walla!!! all the private keys are sitting there.
Just having such possessions and not taking care to make it impossible to find the keys seems a bit silly and weird. I don't side with the criminals, but logically, the first thing the criminals do is go to great lengths to make sure the police can't get their hands on the keys. In another case, it can be assumed that pressure was exerted on them, opening all places where the keys were not hidden.
I don't think they are technically inclined though, they are not the hackers, just the keepers of those bitcoin. We will have to find out how the they got the bitcoin from the hackers though, what is their connection. The hackers were caught in 2019, and probably spill their names, that's what I suspect on how the DOJ got a hold of these two and then started to work their way on cracking all their online identifies i.e social media accounts, online wallets and others.