Mr Yang was convicted in September of killing six policemen and wounding three more at the Zhabei Police Station in Shanghai on 1 July in a revenge attack for being wrongfully arrested on suspicion of stealing a bicycle. He lost an appeal against the sentence last month.
His case has become a lightning rod for police brutality and has led to widespread criticism of the police for its summary methods.
For many people Yang has become another victim who took the law in his own hands to meet out justice against those who are constantly abusing the poor and the more marginalised segments of the population.
At the start of the appeal last month, about a dozen protesters donned t-shirts featuring Yang's face before they were quickly taken away by police
Underhanded actions by the authorities during Yang’s trial and the speed with which the sentence was executed show how the government is trying to suppress dissent in a country where unrest is becoming increasingly widespread.
Yang was not allowed to pick his own attorney even though his father had found a lawyer. Instead a lawyer from the Zhabei district government was appointed to act on Mr Yang's behalf.
A well-known criminal lawyer had accepted to plead Mr Yang's case in appeal but here too the family was thwarted by the court.
His execution was also marred by oddities. Wang Jinmei, Yang’s mother, visited her son just three days ago, but was not told that it was the last time she would see her son alive.
His family, which lives in Beijing, was told only last night of this morning’s execution.
