Criminal justice

Scenori: A confidence purchase is when the offender sells a small amount of drugs to informant or undercover officer gains the confidence of the drug trafficker. This is done in hope of doing a much larger deal at another date with the same drug trafficker , which would lead to a greater offense level of drug sale and a subsequent arrest.
Mike goes to the drug trafficker and observe the severity of the wounds. The
trafficker tells Mike that he knows he is going to die. Mike ask him if he is going to die. Mike ask him he is the main dealer of the drugs in this case and he confesses that he is. Mike asks who the shooter was,
and the trafficker identifies him as John Smith, a drug dealer who threatened him
earlier for selling drugs in Smith's territory.
The informant tells make that he is sure that John Smith was the shooter even through the had already left the hotel room when Smith entered it. The drug trafficker was not advised of his rights prior to telling Mike that he was the local dealer. The trafficker miraculously survived the shooting.
Discuss what the drug trafficker told you at the scene . Could his statement be used against him.
Is the testimony of the informant that the shooter must be John Smith admissible in court?