PETALING JAYA, MALAYSIA - A case of jealousy landed a 22-year-old Malaysian prostitute behind bars in London for at least 15 years for the murder of a graduate.

Noor Azura Mohd Yusoff was on Friday convicted by the Old Bailey of killing Xie Xing Xing, 23, who was decapitated while alive and her body dumped in the River Thames in April last year.

Her boyfriend Trach Lon Gian, 27, of London, was also convicted of the murder and jailed a minimum of 22 years.

The court was told that Noor Azura was jealous of Xie and had sent a text message threatening to kill her just days before her death.

In March, Noor Azura returned to her home in New Cross, London, and found Xie taking part in pornography and a cocaine party.

Xie's corpse was found two weeks later in the South Dock Marina in Bermondsey.

Seven weeks later her head was found nearby wrapped in plastic.

"The attack was vicious and cruel. Not only was she stabbed twice in the neck, she was decapitated whilst alive," judge Giles Forrester had said.

A post-mortem showed 37 separate knife wounds on Xie and her head was cut while she was alive.

A Vietnamese accomplice to the murder is believed to have fled the country.

Police said Xie came from Sichuan, China, and was a good student at Liverpool University.