If the person is a CI, you may not be able to know the identity unless there is a motion to produce the name. Otherwise they could not prove an agreement.
One can still be prosecuted under conspiracy to commit a crime and the commission of that crime, even if the seller is not identified. A common reason the seller is not identified is they are an undercover officer. The scenario you have described is a hub-and-spoke conspiracy.
I believe they call them "confidential human source."
The response above is not intended as legal advice. This response is for educational purposes only. I have not met with you and I am not knowledgeable about the specific details of your case. Each case is unique and different. Therefore, it is highly recommended that you contact and meet with a licensed criminal defense attorney to discuss your specific circumstances. In addition, an attorney-client relationship is not created by virtue of this response.
Yes, Many other factors must be considered to answer your question with an answer it deserves.
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