A 71-year-old man has been arrested in Pakistan in connection with the murder of Pc Sharon Beshenivsky, who was shot while on duty in 2005.
West Yorkshire Police said Piran Ditta Khan was held on Tuesday following an operation involving the National Crime Agency and local partners.
He appeared in an Islamabad court on Wednesday, where his extradition was discussed.
Khan was remanded in custody to next appear at court on January 29.
Pc Beshenivsky was shot while responding to a robbery at Universal Travel in Morley Street, Bradford, on November 18 2005.
Detective Superintendent Mark Swift said: “I would like to thank the National Crime Agency officers in Pakistan and partners who have made this arrest possible.
“This is a major development in this long-running investigation and their assistance in this matter cannot be understated.
“We are continuing to liaise with partners in Pakistan to process Khan’s extradition with the intention of returning him to the UK to face court proceedings.”
Pc Beshenivsky was a 38-year-old married mother of three with two stepchildren, and was a probationer with only nine months’ service when she was killed.
Her colleague, Pc Teresa Milburn, was also shot but survived to later give evidence at the trial of members of the armed gang who were charged with being involved in the murder.
Six men were later jailed at Newcastle Crown Court, but Khan, a former bouncer who was suspected of being the gang organiser, had fled abroad.
In 2016, West Yorkshire Police issued a fresh appeal for find him as he remained at large despite a £20,000 reward for information leading to his arrest.
West Yorkshire Police Federation said officers were delighted at the breakthrough.
Federation chairman Brian Booth said: “The persistence to capture and bring to justice all those involved in the murder of Pc Sharon Beshenivsky has to be applauded.
“I know my colleagues within West Yorkshire are delighted to hear about the arrest of Piran Dhitta Khan, and will now be watching closely the wheels of justice turning in this case, and how this plays out.
“The murder of Sharon and the attempted murder of her colleague Pc Teresa Milburn sent a shockwave not only through West Yorkshire but throughout the world.
“We still mourn the loss of Sharon and I wish to pass on my thanks, on behalf of my West Yorkshire colleagues, to the National Crime Agency in Pakistan for making this arrest possible.”
A memorial marks the spot where Pc Beshenivsky was shot at close range outside the travel agents.
The UK’s High Commissioner to Pakistan said “a tremendous amount of work” had gone on behind the scenes with local organisations and the British police.
Christian Turner said: “Teams at the British High Commission in Islamabad, West Yorkshire Constabulary, and our partners in Pakistan, have worked together to make this possible.
“We will continue to liaise with our partners in Pakistan to ensure Mr Khan’s extradition moves forward as part of the search for justice for Pc Sharon Beshenivsky.”