Glasgow gangland figure Kevin "Gerbil" Carroll put out a £100,000 contract on one of the men blamed for killing him, a murder trial has been told.
Det Con James Sloan said the man - who cannot be named for legal reasons - also told police about people who were interested in harming Mr Carroll.
The police officer was giving evidence at the trial of Ross Monaghan.
The 30-year-old denies denies shooting Mr Carroll dead at the Asda car park in Robroyston, Glasgow, in January 2010.
The jury was told that DC Sloan spoke to the man - who was an associate of Mr Carroll - after the shooting.
He refused to give a formal statement, but did give information to the inquiry.
Defence QC Derek Ogg asked DC Sloan: "Did this man say he was no longer an associate because he understood that Gerbil had offered £100,000 for a hit on him?" The detective replied: "That's correct."
The man also gave police information about a number of people interested in doing serious harm to Mr Carroll, DC Sloan said.
Mr Monaghan's legal team has lodged a special defence blaming eight men, including William Paterson who is believed to be in Spain, for the shooting.
The jury heard that DC Sloan also spoke to Scott Bennett, a nightclub owner, about a mobile phone number of interest to the inquiry.
He took a statement from Mr Bennett in a supermarket car park in Bearsden on 10 September 2010, because he refused to go to a police station.
Advocate depute Iain McSporran, prosecuting, asked DC Sloan: "Did he give information about a mobile phone number ending in 1210 that the investigation was interested in?" He replied: "Yes."
Mr Bennett's statement was read out in court and in it he said that he was looking for a roofer to repair a leak in the roof of his Clydebank nightclub.
He said in the statement: "I got the number from a mate of mine for Ross Monaghan. He's a pal of mine. I know him as Hugo. It's rhyming slang. Hugo Boss, Ross."
Mr Bennett told DC Sloan that he was called twice by the number ending 1210, which he believed was Mr Monaghan's number.
Gillian Rankin from Addiewell Prison told the court that two days after the shooting of Mr Carroll, Mr Monaghan and William Paterson visited Paul Lyons in the jail.
She told the court that all visitors to the prison have to be photographed and fingerprinted and go through airport-style security before being allowed access to prisoners. There are also sniffer dogs patrolling the jail.
Mr Ogg asked her: "Any visitor would be aware of this?" She replied: "Yes."
It is alleged that while masked and acting with others, Mr Monaghan murdered Mr Carroll by repeatedly discharging loaded handguns at him, shooting him on the head and body.
He is further accused of, while acting with others, attempting to defeat the ends of justice by disposing of a revolver, pistol and ammunition within undergrowth in Coatbridge and Airdrie, both Lanarkshire.
It is also claimed a car - bearing false number plates YF 55 EZZ - was set on fire.
Mr Monaghan also faces a number of firearms charges.
He denies all the charges against him and has lodged a special defence of incrimination against eight men.
The trial before judge Lord Brailsford continues.