The only other option the UP police have is asking a federal prosecutor to take the case. And that's only if there's some credible evidence of a federal law violation.
I'm not generally one for expanding federal jurisdictional reach, but there's a much clearer federal connection for: internationally imported shipping containers leaving a federal port facility on a (primarily) federally regulated mode of transportation devoted (primarily) to interstate commerce... than there is for 90% of what legally gets classified today as federal jurisdiction.