A husband who hacked his brother-in-law to pieces was caught when a severed thumb 'fell from the sky' after being dropped by a bird, a court heard .
Mohammed Riaz, 33, allegedly kidnapped Mahmood Ahmad, 41, and tortured him to death in an attempt to track down his estranged ex-wife Nahid Ahmad.
He enlisted the help of five accomplices to kidnap, imprison and murder father-of-two Mahmood with a mechanical butcher's saw, St Albans Crown Court heard.
His remains have never been found and the gang was only arrested after a member of the public found Mahmood's severed left thumb in a car park.
A prosecutor told the jury that CCTV footage captured the digit falling mysteriously from the sky and police believe it might have been dropped by a bird which had picked it up.
Riaz, of no fixed abode, denies murder, conspiracy to kidnap, conspiracy to imprison and conspiracy to pervert the course of justice.
Sharif Mohammed, 37, Faisal Chowdhury, 18, Arnold Alexander Yousaf, 18, and Armizada Hussain, 37, all pleaded not guilty to murder and conspiracy to imprison.
Chowdhury and Yousaf pleaded not guilty to the further charge of conspiracy to kidnap and Mohammed and Hussain denied conspiracy to pervert the course of justice.
Riaz's sister Sabra Sultana, 36, from Ilford, pleaded not guilty to conspiracy to imprison and conspiracy to pervert the course of justice.
Stuart Trimmer, prosecuting, told the court that Riaz's obsession to find his estranged ex-wife led him to organise Mahmood's kidnap.
He said: 'This was a planned rehearsed kidnap for the purpose of the torture and perhaps punishment of Mahmood Ahmad.
'The entire remains of Mahmood have not been recovered.
'But it will be quite clear that he was taken alive from outside his house in the early hours of the 7 March and was killed and his body dismembered by the 10 March.
'The body of Mahmood was disposed of so efficiently that only a segment of the hand has been found.
'That appears to have been severed by a tool that bears the mark of something akin to a band saw, like something which might be used in a butcher's shop.
'CCTV footage shows it falling from the sky. How it fell from the sky is unclear, whether a bird took it is unknown.
'These defendants all took part in these events. They were part of a rehearsed plan to take a man off the street to a distant location of the purpose of torture.
'It is plain that such a drastic course of action means each knew what was going on.'
Fast food worker Mahmood, from Watford, Hertfordshire, disappeared after leaving work in the early hours of March 7 last year.
The court heard that on March 10 his severed left thumb, still attached to the knuckles of his left hand, was discovered by a security guard on a street in Ilford, Essex.
Mr Trimmer told the court that Mahmood's brother-in-law Riaz exercised a reign of terror over his wife Nahid and her family - leading to a divorce.
In a bid to track down Nahid, Riaz allegedly hatched a plan to kidnap Mahmood and torture him into divulging details of her new address.
The court heard that on March 7 neighbours witnessed Mahmood being bundled into a car by Chowdhury and Yousaf on the doorstep to his home.
He was allegedly taken to Hussain's home in Manor Park, east London, where he lived with his girlfriend, Sabra Sultana, 36, who is also Riaz's sister.
The jury heard that neighbours heard cries of 'leave me alone' and 'let me go' and a scream 'full of fear or terror' between 2am and 4am on March 7.
Ahmad, who is survived by his wife Farah Manir, was never seen alive again.
Hussain and Sultana are alleged to have cleaned the murder room at a later date and arranged for workers to remove furniture and bathroom units.
However, the court heard that police later found traces of Ahmad's blood on the floor and on the wall in the bathroom.
The trial, which is being presided over by Mr Justice Jeremy Cooke, continues and is expected to last eight weeks.