scbair,
Your analogy isn't correct. First, (unless I missed it) the security guards were not sworn law enforcement officers. The police officer has the legal priviledge of requiring you to pull over. Non LEOs cannot require that (application of force notwithstanding). Second, the accused theif didn't kill himself, which would be similar to running his own car off the road - the security guards killed him.
So, to improve your analogy, try this:
You're driving out of a private lot, and some security vehicle comes out after you, green lights flashing. You paid for your parking, and you know that there's no other reason the security guard may be following you, so you continue on your way.
The security vehicle chases you down, and spins your vehicle out, causing you to crash. You're injured, but it's not necessarially life threatening. But, the security guard doesn't want you to escape, so he gets out of his vehicle, and pins you in yours. Unfortunately for you, he pins you right on a sharp piece of glass, which digs into your chest, slipping neatly between your ribs.
There's a bystander who sees the blood, and pleads with the guards to call an ambulance. Or to at least let you off the glass. The guards refuse, continuing to pin you against the glass, and continuing to push it towards your lungs.
When you die of internal bleeding, or suffocation, is it your fault, or the security guard's fault?