January 2021 Prison for perverted maths teacher A maths tutor who continued teaching while being prosecuted for fondling three of his young pupils has been jailed for 18 months. Yi Liu, 63, abused his position to sexually abuse four young boys under the age of 13 between 2012 and 2018. Following his arrest Liu had been bailed on condition that he have no unsupervised contact with boys under 18. But in August 2018 he was able to continue working unsupervised with children.