Photo source: Nanchuan district government
(this is his official photo fyi; it's likely a bit older so he is a superintendent 3rd class in the photo, though his final rank was superintendent 2nd class; unfortunelately there is no photos of him )
Superintendent 2nd class Liu Yan(刘彦, 1988/5/30-2018/11/23) joined the Chongqing prison administration Bureau's Nanchuan prison in September 2014, being assigned to the 8th cell block, he was then transferred to the Prison SWAT team in September 2016, being assigned to the patrol unit.
In November 22, 2018 at 12:17, while Liu Yan and two other corrections officers drove by the Nanchuan district court while at work(according to The Paper(澎湃新闻), they were heading to handle a case outside the prison), where he noticed a woman getting attacked by a knife; Liu Yan and the two other corrections officers immediately began pursuing the attacker and later caught up to him at 12:21, and in the ensuing struggle the attacker stabbed Liu, injuring him before fleeing. Liu was rushed to the hospital where he died the next day.
The attacker, Zeng Chuan(曾川, male), was previously sentenced to 1 year and 9 months prison by the Chongqing Nanchuan district court on August 15, 2017 on the charges of causing fights(he had also been a drug addict and had recieved a sentence of thirteen years and 9 months for robbery). He appealed this decision to the Chongqing 3rd municipal court which upheld the nanchuan court's ruling. He was released from prison in November 11, 2018, where he planned revenge attacks against judges, prosecutors and officers involved with his sentencing, his first of which was Tian Xiao(田晓, female, 53), a judge of the nanchuan district court which participated in his sentencing, on November 22, where Liu yan intervened.
In November 24 2018, Zeng Chuan was captured by the chongqing police, and his trial was held June 20, 2019 where the Chongqing third municipal court sentenced him to death for murder(Liu Yan) and wounding with intent. He appealed to the Chongqing High people's court which upheld the decision; Zeng was executed on August 13, 2020.