http://invest7xci3j4tfs37zeyxylwmhfnl2nvfbf6geos4xxeh3ejmzntfid.onion/bitcoin-adder/index17.html
You can see, for example, that bc1qf7wj72yuy948fne0me8utw9tuggus9axqgmygs sent 0.01718427 bitcoin to bc1qcllszem674dx2yk6asfhwsqn0xp4mrjpdsc87k on August 14, 2017, between 11:10 and 11:20 a.m. The long strings of numbers and letters are addresses, and if you were in law enforcement or just very well-informed, you could probably figure out who controlled them.