I certainly wouldn't have hung around if I'd just killed a cop who was chasing me, and had presumably called in to let others know.

I would have been on the road immediately, and as far away as possible as soon as possible, pausing just long enough to pick up my passport if it was up to date, across the closest border, and then onward to a country without an extradition treaty.

But those guys that broke out of prison didn't travel very far at all either, given how long they were on the loose.

It is possible that these Fox Lake killers had a car and took off just as you suggested.

Out here in Ohio, I see people leaving their cars running while they go shopping, just because they want the A/C to still be on when they come back out. You could probably grab one of those and have a solid half hour before it even gets put in the system as stolen. If they actually knew how to hotwire a car, they'd be in even better shape, able to grab one from a garage at night, and have a whole lot of hours of free riding time before anyone found it was gone.