Britain has requested the extradition from Pakistan of a man suspected of being a key figure in the alleged airliner terror plot.
Rashid Rauf, a British citizen in his mid 20s, is suspected of having contacts with Islamic militant groups in Pakistan.
Surprisingly, the British government has requested Mr Rauf'sextradition in relation to the death of his uncle in 2002.
There have been unconfirmed reports that the stabbing was an "honour killing".
Mr Rauf's arrest by the Pakistan authorities on 9 August prompted Scotland Yard to arrest 24 men and women in connection with an alleged plan to smuggle explosives on to US-bound aircraft and destroy up to 10 airliners.
Twelve people have been charged in connection with the alleged conspiracy.
A spokeswoman for Pakistan's foreign ministry said Mr Rauf was being investigated for alleged links with al Qaeda and in connection with terrorist threats in Britain and Pakistan.
Pakistani officials have said Mr Rauf, who also holds Pakistani nationality, helped co-ordinate the alleged plot He is believed to have been undergoing interrogation by Pakistan officials.
A Home Office spokesman said: "The UK has submitted an extradition request to the Pakistan authorities in respect of a murder committed in April 2002."
Mr Rauf left his family home in Ward End, Birmingham, for Pakistan in April 2002 shortly after his maternal uncle was murdered.
Mohammed Saeed, 54, was stabbed near his home in Alum Rock, Birmingham, in April 2002.
He collapsed in front of his wife and two children and died in hospital.
Some sources in the community say it was a row over an arranged marriage, while others claim it was a so-called "honour killing".
Last week, a charity set up by Mr Rauf's father, Abdul, had its bank accounts frozen over the alleged abuse of funds.
The Charity Commission froze all the assets of Crescent Relief after claims that money may have been used to fund terrorist activities.
Tayib Rauf, 22, Rashid's brother, was released without charge in relation to the alleged plot.
Twelve people charged in connection with the alleged conspiracy were remanded in custody last week.
Detectives have until Wednesday to question another eight people still in custody.
