No, "pressing charges" is a myth. The feds can (and do) go after anyone they want, whenever they want.

"Want" being the critical word here.

Not sure who you are quoting. I certainly didn't use the words "pressing charges"...

If I detect a crime on my property and don't notify the police (ie file a complaint), the police aren't going to go after anybody because they don't even know something has happened.

In this case you could say it's been in the news enough that there should be an investigation. Maybe there is, who knows? If the victim isn't going to cooperate, it's going to be a difficult investigation and prosecution and those resources may be better spent elsewhere.