Johannesburg - The former Parktown Boys' assistant water polo coach has been found guilty of 12 counts of assault and 144 of sexual assault.

Earlier in his trial Collan Rex, 22, pleaded guilty to 144 charges of sexually assaulting 12 schoolboys aged between 13 and 16, in a harrowing reign of terror which lasted from 2015 to 2016.

Rex who appeared at the Gauteng South High Court sitting in Palm Ridge, admitted to lewd acts of grabbing and squeezing boys' genitals on numerous occasions as well as rubbing his penis against several learners while they were fully clothed; an act known as dry humping.

During the trial, all the boys who testified said that Rex had strangled them a number of times, while one even passed out.

Some of the learners, who cannot be named to protect their identities are still at the school, while others have since left.