It is my belief that when the Police Officer says cooperate and we will help your case in the long run...you need to wait. I have seen too many people come and hire me after they were promised help in their criminal charges. All they had to do was a couple of "buys" for the narcotics officers. A couple of buys turns into 5, then the officer can't be reached to discuss the matter with your prosecutor.
What really should happen is that you indicate a willingness to cooperate. Take the officer's cell phone and immediately hire a lawyer to discuss the pros and cons of cooperation. Remember, the officer isn't the one filing charges and prosecuting you. In Nebraska, I rarely see an officer substantially affect the outcome of a defendant's case by way of cooperation. Cooperation immediately after an arrest is like buying the "extended-warranty" for a new Honda vehicle. You're in the dealership, they already got you spending thousands of dollars, and they hit you with this last question. Can you really say no??? The answer is let me think about it...and then contact a lawyer!