He used to work in the US, but at the time of the US prosecution and his arrest he was back in Wolfsburg, and the vacation was in Florida.

The English Wikipedia article isn‘t terribly clear about that.

Do you have a source for this?

CNN reports that he was on vacation to Florida and was arrested in the airport awaiting a flight home to Germany [1].

[1] https://money.cnn.com/2017/03/17/news/companies/volkswagen-e...

He is a German national though. Bit of a confusing situation.