I don't think they are providing fake evidence as much as just not disclosing everything. "The DEA told me to watch for his car and pull him over for a traffic

I don't think they are providing fake evidence as much as just not disclosing everything. "The DEA told me to watch for his car and pull him over for a traffic violation. I noticed the suspect change lanes without signal and I pulled him over." They just leave out the first sentence. The problem is when they don't disclose properly the worst case scenario (for the government) is just a mistrial or acquittal. In cases where the defense suspects parallel construction, they need to put the officers on the stand and ask them straight out "did you receive any information from a federal government agency about the defendant?". Make them either give it up or perjure themselves.