Fort Worth Police Department / AP A mug of Aaron Alexis, arrested in September, 2010, on suspicion of discharging a firearm in the city limits.

The gunman in this month’s bloody rampage at the Washington Navy Yard claims that attempts at government mind control drove him to the crime.

The FBI on Wednesday released notes retrieved from the shooter, Aaron Alexis, providing a window into a paranoid mind that felt under siege by “low-frequency,” Navy-developed electromagnetic waves.

“Ultra-low frequency attack is what I’ve been subject to for the last three months. And to be perfectly honest, that is what has driven me to this,” Alexis wrote before killing 12 and dying himself in a shootout with authorities, according to the FBI.

Messages found scrawled on the side of the navy contractor’s Remington 870 sawed-off shotgun read, “End to the torment,” “Not what y’all say” and “Better off this way.”