It's non-trivial to go from a list of transactions to having a nicely indexed DB with convenient tools for investigating.
It's correct that you can trace transactions through the blockchain, but in practice you need something like Reactor to be built and maintained. It's not going to be obvious to police, because the skill is a specialized thing in the domain of coders, and those coders have to have a reason to look at blockchain.
The police department will ask IT, they will Google it, and tell the cops to use one of the various commercial options used to deanonymize wallets and transaction trails. A credit card payment or trial sign-up later and if the service is any good, they'll have what they need.
I'd put anything available to the general public in the "trivial" camp, even if the underlying tech is fantastically complex or difficult.
It's correct that you can trace transactions through the blockchain, but in practice you need something like Reactor to be built and maintained. It's not going to be obvious to police, because the skill is a specialized thing in the domain of coders, and those coders have to have a reason to look at blockchain.