U.S. Border Patrol agents freely used the derogatory slur tonk to describe unauthorized migrants on government computers, at times while joking about killing or beating them, according to emails and text messages disclosed to HuffPost under the Freedom of Information Act.

The documents, from 2017 to 2020, reveal yet another instance of the Border Patrols use of a slang term that officials in Washington have condemned but have struggled to stamp out. This is the second disclosure that Border Patrol personnel used the word in internal communications since HuffPost first requested a global search of its use among Border Patrol agents four years ago.

The origin of the term is uncertain, but most insiders believe it comes from the sound made by bashing an arrested migrants head with a government-issued flashlight. Some of the records reference that origin story, with one agent writing: ah, savor the sound.