Chan Tong-kai, the murder suspect whose case sparked a political crisis in Hong Kong, has been released after serving 18 months in prison.

Mr Chan, a Hong Kong resident, is suspected of murdering his girlfriend, Poon Hui-wing, while on holiday in Taiwan last year. By the time Ms Poon’s body had been discovered hidden among park bushes, Mr Chan was back in Hong Kong, where he later confessed to the crime.

He could not be easily extradited to face trial in Taiwan, despite requests from the island’s authorities, because no formal extradition agreement exists.

Instead, Mr Chan, 20, was charged in Hong Kong with the lesser crime of money laundering, which landed him in prison.

As his case unfolded, the Hong Kong government launched a new proposal in February that would explicitly permit extradition to other jurisdictions, and crucially, allow foreign and Chinese nationals – even those transiting through the city – to be sent to mainland China for trial.