The killing was one of three murders committed by the gang during a five- week spree of violence aimed at suspected drug dealers in London, the Old Bailey jurors were told. The gang members spoke with Jamaican accents and had made several telephone calls to Jamaica after two of the killings. Hyrone Hart, 28, of Junction Road, Handsworth, Birmingham, and Kurt Roberts, 19, of the Notre Dame Estate, Clapham, south London, have pleaded not guilty to three murders, two attempted murders, firearms offences and robbery. Mr Roberts also denies one charge of rape.
Andrew Munday QC, for the prosecution, described how, in one killing, two girls aged seven and one were sandwiched under a mattress by one of three men, armed with a gun and knife, who forced their way into the family's home in Tulse Hill, south London, in June.
Mr Johnson was stabbed in the neck when he tried to grab the gun. The family was taken to a bedroom, where the children were put under a mattress, while the gang searched for jewellery and cash. Mr Johnson and his wife were tied up with flex and told to lie on the floor next to the bed.
The gunman then leant over and shot Mrs Johnson in the head at close range, the court was told.
A second bullet, believed to have been intended for her husband, passed through the piping of the mattress, a magazine rack and into a wall, said Mr Munday.
"Having heard shots and not knowing what had happened to his wife, Mr Johnson decided to lay and play as if dead," he said.
After the gang left Mr Johnson sought help but his wife died later in hospital.
Four days later the same gang was responsible for the murder of Michelle Carby, 35, a suspected crack cocaine dealer, it was alleged. Mrs Carby was tied up in her lounge and shot twice through the back of the head, while her children, girls aged three and twelve, and a nine-year-old-boy slept upstairs at their home in Stratford, east London.
The distraught children discovered the body and ran into the road. "They were knocking on doors and seeking help," Mr Munday said. "One told a neighbour, `My mummy's dead'."
In the third murder, Patrick Ferguson, 35, a cannabis dealer, was shot in the face as he opened the front door of his girlfriend's home in Kingsbury, north-west London, in July.
His partner saw the killing from the top of the stairs. Mr Munday said the same gun "was used to execute three of the victims".
Mr Roberts is also accused of raping a woman on a kitchen floor while ransacking her boyfriend's flat in Clapham, south London. The gang stabbed the boyfriend and beat him, causing one of his lungs to collapse. Mr Munday said it was probable the gang had got the wrong address.
Forensic science evidence, recovered items of jewellery and calls made from mobile phones linked the men to the crimes, the jury was told.
The trial continues.