Plea Bargain For Testimony

What is the name of your state? West Virginia. My brother was charged with conspiracy to opperate a meth lab. Five people got caught red handed opperating a meth lab. They all took a plea bargain and got probation, in the plea bargain they all agreed to testify against my brother. My brother was not at the meth lab when they got raided. But they all said he delivered an ingredient to make the meth. They said the ingredient was in a pop bottle, but they all have different storys, one says it was a bottle with black tape on it, another says silver tape. One says it was day time when he was there, and another says it was night time. My question is. Can my brother be found guilty, just on they're testimony, just because they all took a plea bargain? The state has no other evidence that my brother was involved with these people except for they're word. I found one West Virginia Supreme Court case, so far. State v. Swims that states. In this state and the rest of the country. A person can not be found guilty because some one else took a plea bargain, guilt must be proven based on the evidence presented. To me that statment is alittle vague, because they're testimony is considered evidence. Please submit any case law with your answer. Thank you.