A man accused of murdering a former police officer "laughed like it was a joke" and licked the knife's bloody blade following the fatal stabbing, a court has heard.
Mohammed Hirsi and Ameen Jogee both from Leicester, deny murdering Paul Fyfe at his girlfriend's house in the Rowlatts Hill area of the city last June.
Yvonne Coen, prosecuting, described how Hirsi stabbed Fyfe through the heart after a row at the house of Fyfe's girfriend, 30-year-old Naomi Reid, while Jogee watched from the doorstep.
The court heard that Jogee, a drug dealer, and his friend Hirsi visited Reid's house at midnight on 10 June, appearing angry and aggressive after a friend refused to let them in his house.
They were both drunk and Jogee had taken cocaine, the court heard.
Jogee grabbed a knife from a block in Reid's kitchen after they took some cocaine and waved it around, threatening to "shank" the friend who had not let them into his house.
Reid wanted the pair to leave before Fyfe arrived at the house but the pair laughed and said they could "take Paul out".
They left the house but returned shortly afterwards, after Reid sent Jogee a text telling him not to bring Hirsi to her house again.
Father-of-three Fyfe, a former detective constable with Leicestershire Police, regularly stayed at Reid's house after separating from his wife of 28 years in February last year.
He met Reid, a mother of two who was being monitored by social services due to her involvement with drugs, in a club at the start of last year, while her husband was in prison serving a lengthy term for drugs offences.
Fyfe, who was then working as an independent legal adviser to law firms in the Leicester area, was stabbed after he returned to Reid's house in the early hours of 10 June.
Miss Coen alleged Hirsi stabbed Fyfe in the hallway while being egged on by Jogee who was standing on the doorstep.
A post mortem examination showed Fyfe died from a single stab wound to the chest.
The murder weapon has never been recovered, the court heard.
Jogee and Hirsi both deny murder.
In police interview, both blamed each other for the stabbing.
Hirsi, who the court heard laughed when he was arrested shortly after the murder, told the police it was Jogee who was responsible.
But Jogee told police he did not know Fyfe had been stabbed until they had left the house and he saw the knife.
He asked Hirsi what he had done and he laughed "like it was a joke" and "licked the blade of the knife in front of him", Miss Coen told the court.
The trial at Nottingham Crown Court continues.