The two guards also allegedly falsified log entries to show they had regularly checked on inmates — though they hadn't actually done so.
Matthew Bowen, who referred to migrants as "subhuman" and "mindless savages," pleaded guilty to a misdemeanor charge for violating the man's rights.
The Boyert Shooting Center in Katy said its summer sale was meant to celebrate teachers, but some have called the messaging insensitive.
Mississippi communities were reeling Wednesday following the arrests of nearly 700 people who officials said were working without legal documentation.
Officials said the shooter was killed at the scene. The attack happened mere hours after a deadly mass shooting in El Paso, Texas.