I could make an argument both ways for whether or not they are admissible. Even if they are, the state would need to lay the proper predicate in order to admit them in trial.
Cases that require or even use confidential informants can be particularly difficult for the state to successfully prosecute. Even at trial an experienced defense attorney can often convince a jury that the CI has no credibility and that the CI himself may be responsible for any evidence against a defendant.
I recommend you consult with some experienced criminal attorneys.