Hong Kong  - A man who strangled a woman and later told her family to pay a ransom for her safe return has been jailed for life after being found guilty of murder, a media report said Tuesday.

A judge sentenced So Kam-tong, 25, to life in prison for murdering Yau Hiu-yin, 21, after a jury returned a unanimous guilty verdict, the South China Morning Post said.

So also received a concurrent jail sentence of five years and four months after pleading guilty to blackmailing Yau's family.

The judge described the blackmail as cruel since So knew the woman was dead.

So attacked Yau after the woman finished her shift working for an airline at Hong Kong International Airport. He promised to let her go if she revealed the PIN number of her bank card.

But he strangled Yau shortly after she had revealed the number. Her badly decomposed body was found in a culvert about a week later near a housing estate in the Tai Po district of the city.

So then sent text messages from the woman's mobile phone to her boyfriend and family seeking a ransom.

Yau's father arranged a 100,000 Hong Kong dollars (12,820 dollars) ransom payment, which the boyfriend Ryan Hui left at an agreed location.

Police followed So after he went to pick up the money and later raided So's home where they discovered the ransom money and other cash stolen from Yau's bank account.

So testified that he had meant to choke Yau into unconsciousness, not kill her. (dpa)