There seem to be two potential moments of culpability here -- chronologically, the first was whether M'trice should have been released as she was, and the second was whether anyone had direct responsibility for murder.
I think the biggest culprit here is an overall lack of humanity and decency on the part of many people beginning at the restaraunt and ending when she walked out the door at the police department.
First, 89 dollars on a bill that was volunteered to be paid. Maybe California is different, but I can call Pizza Hut here in NC and give my credit card number and they will deliver pizzas to my children at home when I am at work or otherwise unable to be at home to feed them. They don't refuse because I don't fax them a signature. (You can pay for nearly everything on the planet with a credit card WITHOUT a signature.) Why did they feel it so necessary to send someone to jail for less than 90 dollars and not just attempt to take the credit card from her grandmother?
Were the owners or managers criminally responsible? Of course not, but when you look at another human being in the eyes and make judgments on situations that are so obviously bizarre without wondering what may be going on behind it or without feeling anything other than aggravation or disdain, then maybe the next person you should look in the eyes should be yourself.
Secondly, it may be procedure to release (dump) a beautiful young woman out on the streets in the dark in the middle of nowhere without money or a phone and WAY far from home at the PD. So, officially that alone does not make them criminally culpable. However, morally there are so many things they could have done.
Since when do we not care about another living, breathing human? I just cannot fathom being a civil servant with no spirit of servitude. I've worked in medicine for many years and I know that we tend to get hardened to the drug seekers and the malingerers and people who use the ERs like a doctor's office, etc.; however, if you allow yourself to pass judgment on everybody who comes in the doors based on the patients you have seen before, then somebody who really needs your help is going to receive inadequate or inappropriate treatment for their illness. Each case is individual and if someone has become so hardened or so burned out by their job that everybody is bad and you have no generalized concern for a HUMAN, then it's time to find a new profession. Following the book is not an excuse for not following or having a conscience.
Small seemingly inconsequential decisions made by numerous people that night equalled the death of this beautiful young woman. Sad, sad, sad. There were so many people whose path she crossed that night who had the ability to be a hero, unfortunately none of them were up to the task.