Comm sabotage of some sort is actually easy to prove.
1. Question to any of the SS on stage: “Were you notified there was a potential shooter and that you needed to get the President off stage?”
2. Question to all of the SS off stage: “Did you use to Comm to notify any other agents there was a potential shooter on site?”
No on one.
Yes on any two.
Conspiracy proved.
That said—if I were doing the conspiracy I would jam the radios.
Under that scenario nobody in the Secret Service or local law enforcement would know what was happening during critical moments.
Here is a Homeland Security link on this exact topic:
https://www.dhs.gov/sites/default/files/publications/JammingFact_121416-r1-508.pdf
Make sure Comer knows this information.