Officials were led to Mr. Winters after obtaining information from Regpay, a third-party billing company involved in the distribution of child pornography on the Internet.
Correct...and they were probably getting that information there due to information gleened from victims that were not U.S. citizens.
The article says also:
Some of the boys in the material were as young as toddlers, agents said. Many of the recovered images showed children -- mostly young males -- identified in the ICE National Child Victim Identification Program database as child victims in other cases in the United States, Eastern Europe and Russia.