Random question, but who drives the safety cars?

Not sure why this popped into my head, but curious who drives the safety cars in IMSA-sanctioned events. Google did not provide any help so asking here. In IndyCar for example they utilize former series drivers. F1 of course has had ex-driver Bernd Maylander, and I believe the WEC has ex-drivers as well. Is this the case for IMSA, or is it just series staff who typically drive?