Can a police officer bind a prosecutor to an agreement made with a confidential informant? Any case law??? Any help would be appreciated. Thanks.

The short answer is no. Police officers have no authority to make plea agreements. If the police officer wants to make a binding offer to a CI, he needs to get a prosecutor with jurisdiction over the matter he seeks to use as a bargaining chip, and get an agreement finalized. There are lots of cases on this, but I'm going to let someone else do the research.