China's police are under fire this week as citizens blast Beijing authorities' decision not to prosecute police following the death of a 28-year-old environmentalist, Lei Yang.

Many observers see this as a landmark case that flies in the face of pledges by China's leaders to prevent miscarriages of justice and curb the arbitrary exercise of state power.

The case is also drawing attention because college graduates are the ones speaking out. Thousands of alumni of Lei's alma mater, the prestigious People's University, and other top schools have petitioned online against the authorities' decision.

Lawyers, family members and supporters declined to be interviewed about the case. Many of their social media postings have been censored, and many facts about the case have not been made public.

What is known is that on the night of May 7, Lei left his home for the airport, intending to pick up relatives. Prosecutors allege that, on the way, he visited a foot massage parlor, of the sort that are often thinly disguised brothels, and paid for sexual services there. Prostitution is illegal but commonplace in China.

When questioned by plainclothes police, Lei allegedly struggled violently and tried to escape. Prosecutors say police put him in a chokehold and stepped on his face and neck. A little over an hour later, Lei was dead.

Police said Lei suffered a heart attack. Prosecutors later said Lei choked on his own vomit. Police also said that video footage they shot of the incident was lost or damaged. The encounter was apparently random and not related to his environmental work.

Criticism, but no prosecution

Last Friday, Beijing prosecutors issued a statement saying police exceeded the bounds of reasonable law enforcement, that they should have taken him to a hospital in a timely manner. They add that the police hid, fabricated or misrepresented the facts of Lei's case and obstructed an official investigation into it.

But they also said the police had repented, and their infractions were minor, and therefore no charges were brought against them.

On Thursday, police announced that the deputy head of the local police station involved in the case and other people involved were fired from their jobs, kicked out of the Communist Party or given other administrative punishments.

In a social media post Thursday, Chen Youxi, a prominent lawyer representing the Lei family, said the family was unable to withstand the mental anguish of the case, and had dropped plans for further legal action.

One conclusion observers are drawing is that authorities decided to placate law enforcement.

"I suppose they had complex considerations," Tong Zhiwei, a law scholar at the East China University of Politics and Law in Shanghai, said of the authorities, "which may have included worry that they would hurt the policemen's enthusiasm in performing their duties."

In addition to fighting crime, Chinese police are responsible for suppressing political dissent, a task the government euphemistically calls "maintaining stability."

"As a legal scholar, my view is that the four or five police in this case, or at least some of them, should be convicted," Tong says. "I won't conceal my opinion."

Another common perception here is that this incident generated seldom-seen animosity toward authorities among China's college-educated citizens. Tong says this is simply because, in Lei Yang, they see themselves.

Contrasting cases

Other commentators have contrasted the fate of Lei Yang with that of Jia Jinglong. Dissatisfied with government compensation for the demolition of his home, the 30-year-old farmer killed a village official with a nail gun.

Jia was executed last month, despite a public outcry. In comparing the two cases, some believe that Chinese authorities can kill civilians virtually with impunity, but civilians who kill authorities — an act that suggests violent revolution — will be put to death as a warning to others.

China's leaders have insisted, however, that they want justice to be apparent in every court case, and they want public trust in China's judiciary restored.

Some observers have been heartened by the reversal of several miscarriages of justice. In the latest, China's Supreme Court exonerated a man who had been executed 21 years ago for a rape and murder to which another man later confessed.

Police powers have steadily been growing. Spending on domestic security reportedly outstripped China's military budget in 2013.

China's Constitution specifies that police, prosecutors and courts are supposed to check and balance one another.

Copyright 2016 NPR. To see more, visit http://www.npr.org/.