Ms Xie's corpse was found in a bag in the River Thames

A jealous girlfriend has been jailed for life for murdering a young Chinese graduate whose headless body was found floating in a marina in south London.

Xing Xing Xie, 23, was decapitated while alive and her body dumped in the River Thames at Rotherhithe.

Noor Azura Mohd-Yusoff, of Ealing, west London and her boyfriend Trach Lon Gian, of Deptford, south London, were convicted of murder at the Old Bailey.

Another man wanted over the murder in April 2007 has fled the country.

Modh-Yusoff, a 22-year-old Malaysian prostitute, was sentenced to serve a minimum of 15 years while Gian, her 27-year-old Belfast-born boyfriend, must serve at least 22 years.

The brutality and savagery shown by Xing Xing's killers is something I have not come across before Detective Chief Inspector Carl Mehta

Gian was also found guilty of perverting the course of justice by disposing of the body.

Jailing the couple, Judge Giles Forrester said: "The attack was vicious and cruel. Not only was she stabbed twice in the neck, she was indeed decapitated whilst alive."

The court heard during the trial that Modh-Yusoff was jealous of Ms Xie and sent a text message threatening to kill the victim just days before her death in April 2007.

In late March, Modh-Yusoff returned to the couple's home in New Cross, south east London, to find Ms Xie there following a 36-hour pornography and cocaine-fuelled party.

Two weeks later her corpse was discovered by a couple who lived in a house boat in the South Dock Marina in Bermondsey.

Seven weeks later the victim's head was found wrapped in black plastic bin liners in an adjacent dock.

'Beggars belief'

Tests showed Ms Xie had her head cut off while she was still alive and was intoxicated with a potentially lethal level of cocaine.

A post-mortem examination showed 37 separate knife wounds.

Chanh Ngo, from Vietnam, is also believed to have participated in the murder but has since fled the country.

Detective Chief Inspector Carl Mehta, who led the investigation, said: "The brutality and savagery shown by Xing Xing's killers is something I have not come across before and beggars belief."

Mr Mehta said Ms Xie came from the Sichuan province of China, from a well respected academic family background and was a successful student at Liverpool University after she came to the UK in 2002.

"Her family have had to suffer the loss of a daughter many thousands of miles from home, in an unfamiliar city, and in the most harrowing and tragic circumstances."