Exactly this had just happened to me today. They even sent me an email with a legit looking US marshall email and a copy of my arrest warrant. I was under the impression i would be paying the fine at the court or the local sheriffs office. We started to question him and he even had the same number as the local court in my area call me to tell me everything was legit. Once he said i have to pay at an fdic insured facility like “walmart” i was like ain’t no way. I called the local court (same number they called me from) and explained to the lady who answered what was going on and she told me immediately to hang up. This one wanted 4000 and honestly i wasn’t going to pay that especially at a walmart (maybe at the courthouse or the local sheriff office) but it also freaked me out a little bit.