The couple were shot dead in their bungalow
A couple, who were victims of a gangland execution, were found with 25 gunshot wounds, an inquest jury has heard.
John and Joan Stirland were killed in a revenge attack in August 2004 after Mrs Stirland's son shot a friend of Nottingham crime boss Colin Gunn.
Their bodies were found by police at their home at Trusthorpe in Lincolnshire.
Gunn has since been jailed for 35 years for conspiracy to murder the couple.
The inquest heard John Stirland was shot at least six times and had bullets fired through his heart, kidney and the back of his neck.
Joan Stirland died of a gunshot wound to the neck, four bullets and four empty cartridge cases were found beside her body.
The inquest at Lincoln Crown Court is being relayed to media at the city's magistrates' court via video link.
Couple's son jailed
Coroner Karon Monaghan has asked the jury to investigate whether police corruption played any part in the deaths and if the police failed to protect the Stirlands.
Jurors are being asked to examine whether police dealt with intelligence properly and have been given a summary of intelligence reports.
Colin Gunn was jailed for 35 years
Mrs Stirland's son, Michael O'Brien, is being allowed to watch the proceedings in jail, where he is serving a life sentence for murder.
The Stirlands fled to Trusthorpe on the Lincolnshire coast from Nottingham, after O'Brien killed Marvyn Bradshaw, 22, outside a pub in Bulwell, Nottinghamshire.
A senior police officer in charge of investigating an organised crime cartel had no idea of its plans to murder a middle-aged couple in a revenge attack, the inquest heard.
The inquest heard senior police officers knew Gunn's organisation, which numbered between 30 and 40, planned to seek revenge against O'Brien.
But detectives did not know of the crime boss's plans to target his mother, a 51-year-old nurse, and his 55-year-old stepfather.
The officer in charge of investigating Gunn's gang today gave evidence at an inquest into the Stirland's deaths.
Known only as Officer D, he said: "I never heard of a threat, or had any knowledge of a threat, to Mr and Mrs Stirland until the day following their murder. I was unaware of who Mr and Mrs Stirland were."
Questioned by the coroner Karon Monaghan QC as to whether there were any threats to O'Brien himself, he said there were five or six attacks following the death of Mr Bradshaw.
Officer D added: "At the time we were aware that Gunn was after O'Brien and details of retribution and reprisals had become apparent.
"But there was no direct references to his (O'Brien's) family."
Gunn, 40, of Nottingham, was jailed in 2006 following his conviction for conspiracy to murder the Stirlands.
Co-defendants John Russell, 29, and Michael McNee, 22, were jailed for 30 and 25 years respectively, in 2006.