Earlier quoted context omitted.
If you look at most mass shootings you'll find articles saying the suspect was "known to the FBI." For some reason they rarely stop them ahead of time. The Whitmer kidnapping is a recent example. Well, I guess they started AND stopped it in that case.
That's because most mass shootings have no crime committed until the suspect opens fire.
I'm pretty sure it's illegal to plan a murder. Also, in many of the FBI cases there are undercover agents imbedded with the group. The Whitmer case being a recent example and they were all arrested before any shots were fired.
https://apnews.com/article/whitmer-kidnap-plot-trial-michiga...