Tsui Po-ko – known to many in Hong Kong as the “Devil Cop” after a spectacular shootout a year ago – was a serial killer, according to the results of a 37-day coroner’s inquest.

A five-person jury declared this week that the dead constable was responsible for the ambush-style shootings in a Kowloon underpass in March 2006 that resulted in his death and that of another police officer. The incident had the ancillary effect of putting Hong Kong’s police force on public trial for corruption, consuming vast pages of coverage in Hong Kong’s fevered newspapers and hours of television time.

Tsui was killed in a murky gun battle on March 17, 2006, along with Constable Tsang Kwok-hang. Constable Sin Ka-keung was wounded. The jury also concluded that Tsui was the killer in two previous unsolved murders: those of Constable Leung Shing-yan, who died in a shooting at a housing estate in March 2001, and security guard Zafar Iqbal Khan, killed during a robbery at a Hang Seng Bank branch nine months later.

The Hong Kong police have spent three decades fighting – with considerable success – an earlier reputation for dodgy dealing, turning a blind eye to drug smuggling and accepting bribes. In the 1970s, when the Independent Commission Against Corruption was formed to clean up the force, many high-ranking police were forced into retirement. According to one history of the police, 119 officers were asked to leave under the provisions of colonial regulations, another 24 were held on conspiracy charges and 36 officers and a customs official were given amnesties.

But there is considerable concern in Hong Kong that whatever Tsui was up to has again diminished the force’s reputation. Attention has largely focused on the jury’s findings.

Thursday’s lead headline on the front page of the South China Morning Post summed it up: “Jury finds Tsui unlawfully killed three.” But nobody bothered to mention that an inquest jury has no place ‘finding’ such things at all. The purpose of a coroner’s inquest is to determine when, where, and how a person died, and who that person was. What such an inquest cannot do is apportion blame or denote liability. That is the arena of a criminal trial.

The jury’s verdict in this inquest wasn’t just unusual – it was unheard of. This was the first time in Hong Kong that an inquest sought to identify a killer.

But that wasn’t the only disquieting aspect of the proceedings. At the start of the hearings, Tsui’s mother, Cheung Wai-mei, was denied legal aid – purportedly because she owned assets worth more than the maximum threshold for entitlement – and only received last-minute, and under-prepared, representation by two lawyers who volunteered their services. Meanwhile, the police spent a year compiling evidence to produce at the inquest.

On top of that, soon after the Tsim Sha Tsui shootings, and long before the much-delayed inquest began, police had already pointed the finger at Tsui, labelling him a rogue cop. Fewer than three weeks after the underpass incident, police linked Tsui to the unsolved 2001 killings. “There should be sufficient evidence to charge the suspect on all three [killings] had he been alive,” the Hong Kong Police security bureau told the Legislative Council Panel on Security on April 6, 2006. A full year passed until there was a public hearing.

Critics have pointed out that Tsui, presumably a clever, street-wise cop, would have been foolhardy to take on two armed comrades in an ambush with only a single, supposedly rusty pistol he had taken in an earlier murder.

Nonetheless, Tsang, posthumously, and Sin were both awarded the Medal for Bravery, for “exceptional courage and gallantry of the highest order during a life-threatening situation.”

What wasn’t decided at the inquest were Tsui’s motives. The suggestion that the police were involved in illegal soccer gambling went unresolved, despite a credible investigative report by the Sunday Morning Post’s Niall Fraser that cited multiple sources saying Tsui had probably gone into the underpass that night to discuss gambling debts with the other officers. The same report quoted police sources as saying that police-gambling links dated as far back as 2000, when they were the subject of a too-hot-to-handle internal investigation.

The police have accepted the jury’s findings. Chief Superintendent Philip Choy Kin-cheung said: “The police will respect the verdicts. It was an open and transparent inquest.”

And well they should. In Tsui, a dead and demonised bad cop, they have a culprit that can be blamed for three unsolved high-profile killings that have embarrassed the police and called into question their position as “Asia’s finest”. It may well have also conveniently buried the investigations into illegal gambling within the force.