Portland

That's one of the pieces that doesn't make sense.

FTA:

"Deschutes County detectives received information Monday from Portland Police Bureau detectives about a man identified as Samson Zebturiah Garner “planning a violent attack during an event” in the county, Sergeant Jason Wall said Friday."

and:

"DCSO and Portland detectives worked for several days to investigate the man, and learned Thursday that Garner had left Portland and was in Deschutes County, Wall said."

So Portland police tipped off the County on Monday, they worked the case together through Thursday when they learned he had left Portland, and picked him up in the county.

But it's not clear where the OG tip came from.

Probably his cell phone spying on him and flagging him on key word searches and texting conversations and other precrime bullshit.

We'll never find out what the evidence was because it will never be made public

We know he had an AR15. That's it.