A police force's failure to share intelligence contributed to the deaths of a couple at the hands of a criminal gang, an inquest ruled.
John and Joan Stirland were found shot dead at their bungalow in the Lincolnshire village of Trusthorpe on August 8, 2004.
Nottingham crime boss Colin Gunn, who had persuaded police officers to provide him with information, and two other men were convicted of conspiring to murder the couple in 2006.
An inquest at Lincoln Crown Court heard that the shooting was a "revenge" attack after Mrs Stirland's son, Michael O'Brien, shot 22-year-old Marvyn Bradshaw dead outside a Nottingham pub in August 2003.
The "criminal community" in Nottingham believed the bullet was meant for Mr Bradshaw's friend and Colin Gunn's nephew, Jamie. He died in August 2004 from pneumonia, six days before the Stirlands were murdered.
After 11 hours of deliberation and an inquest lasting more than three weeks, a jury found that Nottinghamshire Police failed to share intelligence about the threat posed to the couple by Gunn's gang. The unanimous verdict also found that BT operators contributed to the couple's death by passing on information about them to Gunn and his associates.
But the jury cleared Lincolnshire Police of failing to protect Mr Stirland, 55, and his 51-year-old wife after they were asked by Nottinghamshire Police to call in on the couple hours before they were found murdered.
The jury recorded two verdicts of unlawful killing. The coroner, Karon Monaghan QC, said she would consider whether to make a further report following the jury's findings.
After the jury's ruling, Nottinghamshire Police apologised to the Stirland family, saying the couple were "let down" by "organisational failures". Chief Constable Julia Hodson said: "On behalf of Nottinghamshire Police, I would like to say sorry to the family and friends of John and Joan Stirland.
"The policies and procedures in operation today are far more comprehensive and robust, particularly in relation to how we protect witnesses and in particular those whose lives are considered to be at risk."
