Sadly I did hear of a top player recently caught using a computer while taking a rest room break, I'll look for the link
Chess Grandmaster Admits to Cheating by Using Smartphone in Bathroom Stall
This incident happened few years back, and in this case Igors Rausis admitted of using smartphone in bathroom during a tournament. He's the oldest player in the top 100 list of chess players. The chess federation also confirmed the act of computer assisted cheating.
I'm sure that the news that he is cheating have shocked the other players on the said tournament especially for those who are believing in him or for those who have been defeated by Igors Rausis. Anyway, it seems that it is not the first time he cheated while using a bathroom break, I mean he could've cheated already before he was caught.
It is very sad when someone who should be a respectable figure on a honest and respectable sport with a great tradition of fierce but pacific rivalry takes advantage of the rules to cheat. It is very sad particularly to any rival that is actually dedicating all the time and dedication needed to become better and has to face a cheater.
Perhaps the problem with chess is that computers are better than most humans and they are about to catch the grand masters. Eventually, nobody doubts that humans will loose.