Gangster Kwai Ping-hung has been released after serving 17 years in prison.
Reports say he does not hold a Hong Kong ID, but has an American passport, and so was being taken to the airport to be deported to the United States.
Kwai, now 59, carried out about 20 armed robberies over three decades. Kwai and two other infamous gangsters - "Big Spender" Cheung Tze-keung and Yip Kai-foon - were known as "The Three Kings of Thieves."
In 1985, Kwai robbed a watch shop on Nathan Road in Tsim Sha Tsui and stole HK$1.8 million worth of items. He fled after a shoot-out with police, injuring 11 people. In 1994, he robbed $10 million worth of goods from another watch shop in Central and killed a 23-year-old woman during a shoot-out with the police.
In 2001, Kwai and three accomplices shot and wounded two officers in Mong Kok. This led to police issuing a $2 million reward for his arrest and an Interpol red notice.
On Christmas eve 2003, the elite Flying Tigers police squad raided an apartment in Yau Ma Tei and captured Kwai and seized a large quantity of weapons.
Kwai was sentenced in 2005 and jailed for 24 years for charges including possession of weapons and ammunition without a license, use of weapons and resisting arrest. He later had his prison term reduced by a third for good behaviour.