There are no specific "details." There is no on-line database to learn who snithces are. If you are serious about this you want to become a registered informant and put the specifics in writing so the police later cannot say you were not authorized to do what they ask you to and instead arrest you again. Your lawyer should be involved in this because it is up to the DA - not the police - to resolve your current case. If your lawyer won't help with this I suggest you retain a lawyer who will. Please understand that often it is not hard for someone to figure out who set them up... its usually the person they were dealing with prior to the arrest.
I am a former federal and State prosecutor and now handle criminal defense and personal injury/civil rights cases. Feel free to check out my web site and contact me at (212) 385-8015 or via email at Eric@RothsteinLawNY.com. The above answer is for informational purposes only and not meant as legal advice.
You need your own attorney to advise you. It's not as simple as a cop tells you it is.
I am a criminal defense attorney practicing in Nassau, Suffolk and New York City. The above information is not a substitution for a meeting whereas all potential legal issues can be discussed.