Arrested for delivery of a controlled substance, marijuana. I did not participate — what are my chances?

As I am sure you are aware, there are several possible resolutions to a criminal case with respect to being able to "get off."  In connecticut, a charge may be "nolled" or "dismissed" prior to trial.  In order to do this, your attorney would have to convince the prosecutor that you did not deliver any marijuana to your friend.  You say that the cop says that you are the source, but you do not say what he is basing this conclusion on.  I assume that your "friend" provided a statement to that effect?  If so, it would be helpful to obtain statements of other witnesses that can corroborate your story.  The fact that your fingerprints are not on the bag will be helpful, although probably not determinative, of your case.  Of course, the "chances" of getting off will change if you decide to plead not guilty and take your case to trial.  If you do that, the prosecutor will be required to prove, beyond a reasonable doubt, that you actually committed the crime of delivering the controlled substance.  This means that if your attorney is successful in creating a doubt in the jurors minds, you will be found not guilty.  Without looking at the police reports, state's evidence, and any exculpatory evidence, it is impossible for me to say exactly how likely it would be for a jury to find you not guilty.  However, it is clear that although the "beyond a reasonable doubt" standard is difficult for a prosecutor to prove, if your "friend" has provided a sworn statement against you and there is scant exculpatory evidence on your behalf, taking this charge to trial would be a gamble.

With "friends" like that, you don't need enemies, you need a good criminal defense lawyer.  One place to find qualified attorneys is our website, http://attorneypages.com

I think it's relatively unusual for people to be prosecuted for selling drugs, without some physical evidence directly connected to the defendant (you!).  I'd recommend very carefully lawful behavior from this point, and please do not put off finding yourself a lawyer!

Reliable advice depends on giving all of the facts to your attorney, even things that you might think are insignificant, even things that you find embarrassing.  Especially the things you find embarrassing, sometimes, because they are even worse if you have to deal with them in court -- and your attorney wasn't prepared to meet it because you never told.

Being in the wrong place at the wrong time is no crime.  Assuming that the facts are as you say, not having your fingerprints on the bag is pretty convincing evidence.  Also, although you did not indicate, if you have an otherwise clean criminal record that will also weigh heavily in your favor.  However, you've been arrested, and innocent or not you need to get a criminal attorney to help you. 

Try to find one that practices in the locality where all of this happened.  He'll better know the people in the prosecutor's office.  That can be a real benefit in a case such as this.  If money is an issue contact the public defender.  Whatever you do, do not speak with the police until you are represented by counsel.