I watched much of the episode, but I wasn’t paying close attention, and I missed the end. The sense I got was the 60 Minutes was reporting the story from the attitude that the US government is covering something up, and all of the reports from agencies not being able to find anything are because the US doesn’t want anything to be found or are incompetent. By doing this the US is causing further harm to the victims.
The new evidence they found was a guy arrested in the US who might (even probably) is a Russian spy. It wasn’t entirely clear to me that there was any evidence linking the spy to any of the harm (but that might have been due to me not paying too much attention).