I thought they might have been crazies with explosives. But they would've left something to trace back to them.

[Crazies probably wouldn't be this good at covering their tracks. Unless they were some kind of genius crazy, but he doubts it.]

The technician. He wanted to take readings. [How and on what, he doesn't know. Computers and fancy tech elude him.] I told him to stay out of the mines.