Johannesburg - A man alleged to have been part of a gang that shot and killed two police officers on the N3 offramp near Modderfontein in Johannesburg appeared in the Kranskop Magistrate's Court in KwaZulu-Natal on Tuesday.Nhlanhleni Nzama's case was postponed to April 15, Colonel Noxolo Kweza told News24. "He's charged with the possession of [an] unlicensed firearm," she said. Police on Monday announced they had made a major breakthrough in the cracking of a series of cop killings which have occurred around Johannesburg in the last few weeks. It was unclear how Nhlanhleni Nzama had been linked to the killing of Constables Mthokoziseni Myeza and Maisha Mafokoane.They were shot dead by a gang of heavily armed men after they attempted to stop what was said to be a "suspicious-looking" vehicle. A third officer, Steven Mafanelo, was injured in the shooting. One of the gang members, a Zimbabwean national, was shot and wounded during the incident. Police on Monday said the man had since died. Meanwhile, two other men, Sandile Nyathekazi and Vika Nzama, appeared in the Johannesburg Magistrate's Court in connection to the same incident. The men were charged with two counts of murder, one of attempted murder, possession of an unlicensed firearm and ammunition and conspiracy to commit robbery.Their case was postponed to April 14 as they still needed to undergo an identity parade. Earlier on Tuesday, Zitha Nzama appeared in the Johannesburg Magistrate's Court. He was arrested in connection with the murder of another police officer, Constable Frans Ledwaba who was shot and killed as he responded to a robbery at Park Station two weeks ago. According to the charge sheet, Zitha Nzama faced a charge of robbery with aggravating circumstances and murder.As three of the four suspects who appeared in court today bore the same surname, Kweza was asked whether the three Nzama men were related. Kweza said she did not know.