K'Par Rinn was a female Argrathi who administered the memory of a twenty year prison sentence on Miles O'Brien when he was convicted of espionage in 2372. The Argrathi Authority were experts at mind control and Rinn was able to project the entire sentence into O'Brien's mind in only one hour. This was what the Argrathi used to replace a costly prison system.

When Sisko asked that the mind altering be reversed since O'Brien was innocent of the charges, Rinn informed him that the process could not be reversed. (DS9: "Hard Time").

K'Par Rinn was played by Margot Rose. She had previously appeared as Eline in TNG: "The Inner Light", a story which also involved placing decades of memories into someone's mind (in that case, Jean-Luc Picard) in a very short period of time.
K'Par Rinn's name and occupation comes from the script.