The “person of interest” in Sunday’s fatal Christmas parade crash in Wisconsin that killed five and injured dozens is a wannabe rapper who was released from jail days earlier.

Darrell Brooks, 39, who is currently being questioned over the deadly crash in Waukesha, calls himself Mathboi Fly online — and may even have used the red SUV from the tragic incident in a since-deleted video on his YouTube channel.

The crumpled Ford Escape SUV was found parked in Brooks’ driveway after the shocking caught-on-video vehicular assault — but he has yet to...