Lei Yang. [File photo from web]

It was announced on Wednesday that five police officers have been placed under official investigation by Beijing prosecutors, which is looking into the circumstances surrounding the death of a young man during a vice raid.

This move can be considered a step closer to uncovering the truth of how Lei Yang lost his life on the evening of May 7 in northern Beijing's Changping district.

The case has been covered extensively by the media and prompted a huge outpouring on social media sites in China, not only because it concerns whether Lei was innocent but also because the public want to know whether the police officers behaved legally.

Lei's family have filed a report with the capital's prosecutors and are waiting for the result of the autopsy.

The prosecutors' investigation is a response to the public questioning whether the police officers involved in the raid were in some way responsible for his death, and whether the police officers crossed the line by using excessive force in their efforts to uphold the law.

Of course, even for the purpose of determining whether Lei was innocent and whether he died from natural causes or otherwise, a thorough investigation is needed.

The self-justification of the police's actions immediately after the incident, by a police officer who gave a detailed account to the media about what had happened that evening, has been considered as being detrimental to the credibility of the police. But the attitude that the Beijing Municipal Bureau of Public Security displayed on May 19, by saying that it would not shelter any police officers found to be at fault, should serve as an antidote to the belief that justice will not be done in this case.

Given this, the disclosure of the entire truth of what happened that night will prevent the case being judged in the court of public opinion.

That Minister of Public Security Guo Shengkun said on Wednesday that police officers who misbehave in the process of law enforcement will enjoy no shelter from the law is a further sign that justice will prevail in this case, and that the police officers will be punished according to the law if they are found to have overstepped their power.

That marks a milestone in the progress of the rule of law in China.