The international hunt for suspected killer Du Anxiang has already cost more than £1 million (HK$11.6 million), but it has taken more than money to bring him back to Britain to face justice.
When British detectives escorted the alleged killer onto a flight from Casablanca to Heathrow last Wednesday, it was the culmination of a two-year manhunt.
Northamptonshire police said the extradition had been approved by the Moroccan Ministry of Justice in conjunction with the British Home Office.
But in truth, it was a triumph of eight months of behind-the-scenes diplomacy involving politicians and police forces working closely together.
The lack of an extradition agreement between the two countries ensured that despite "getting their man", there was no guarantee Du would ever face a trial in Britain.
In the 17 years before his arrest, only two people had been extradited from Morocco to Britain. The last was in 2009, a man wanted in connection with a £53 million heist in Kent.
As the murders slipped off the front pages, Du laid low thousands of kilometres away in Africa. But all that changed after police arrested him in July.
Britain's most wanted man was held in Sale prison, near the Moroccan capital Rabat, awaiting extradition.
It wasn't until late last year that the British Home Office began official talks about bringing Du back, while away from the glare of the media Michael Ellis, the British lawmaker representing the victims' hometown of Northampton, applied pressure.
A 'special one-off arrangement' had to be put in place and a 'mini-treaty' had to be negotiated for Du's transfer into the hands of British authorities. That was finally signed last week.
After the suspect's return, Northamptonshire's deputy chief constable Martin Jelley said: "I would like to thank all those who have been involved in this successful extradition, including Michael Ellis."
In court, Du, who spoke through an interpreter, gave only an address and his date of birth before being remanded.
Now those who may have helped him evade justice for so long could also find themselves in the dock.
Last July, two men from Coventry and London and two women from Gloucester and Southend, arrested on suspicion of helping Du flee the country, were released on bail. They have not yet been charged.