During his closing speech at the High Court in Glasgow, advocate depute Adrian Cottam told the jurors there was a strong circumstantial case against Thomas Main.
Main, 41, denies murdering 55-year-old Francis McGrow at his home at Hermiston Road, Springboig, Glasgow between October 26 and 27, last year.
Mr McGrow was the brother of underworld boss Tam "the Licensee" McGraw who died in 2007.
Mr Cottam told the jury: "Francis McGrow died in his own living room. He was stabbed in the back, fell to the ground and was then stabbed 37 times in the centre of his chest.
"He was murdered in his own living room. This was a murderous attack leading to the tragic and untimely death of Mr McGrow."
The prosecutor said the question for the jury was who murdered Mr McGrow.
He added: "It is a circumstantial case, but the evidence shows that Thomas Main was responsible."
A call was made to police at 10.06am on October 27, last year, from a phone box in Gallowgate saying a man had been murdered. Two police officers have said in evidence it was Thomas Main who made that call.
Mr Cottam said: "There is only one way he could know about the murder and that is if he was the person responsible."
He said Main had been living with Mr McGrow in his flat for a few days prior to his death.
He added: "Mr McGrow looked after two dogs and when the police arrived at his flat the dogs were friendly, but they were barking."
The jury also heard that tiny spots of Mr McGrow's blood were found on a pair of Main's jeans. But the defence claimed this was transferred while the two men were injecting drugs.
In her speech defence QC Mhairi Richards told the jurors: "You have to be convinced beyond reasonable doubt that Mr Main is guilty."
She added that to find him guilty the jury would need to indulge in speculation and continued: "The Crown is asking you to speculate."