Johannesburg - The family of slain Mozambican national Emmanuel Sithole on Tuesday said they were shattered by his murder.Speaking outside the Alexandra Magistrate's Court, where four young men had just appeared for his murder, Sithole's sister Thandi said the accused should be kept behind bars for a very long time.She became emotional when she was asked what it felt like to see her brother's alleged killers."It was very difficult because they are small children, in their early 20s," she said."But how cruel are they to take someone's life like that," she said.Sithole said she had little faith that justice would be served."The South African justice system is very poor," she said.Asked what kind of sentence would be appropriate for the accused, Sithole said: "Life sentence and no bail."Sithole was stabbed in broad daylight on the streets of Alexandra on Saturday.Pictures of him being attacked and stabbed were published on the front page of the Sunday Times.Three men were arrested for the killing on Sunday, while a fourth was arrested in the early hours of Tuesday.The accused, Sifiso Mzimela, Amanda Sibiya, Sizwe Mngomezulu and Mthinti Bhengu, were charged with murder and robbery.After the proceedings, National Prosecuting Authority head Mxolisi Nxasana and Gauteng Premier David Makhura addressed the media.Nxasana said he believed the state had a strong case against the accused. He urged the Alexandra community not to take the law into their own hands, but allow justice to take its course.There has been speculation that the attack on Sithole was linked to other xenophobic attacks around the country over the last week.Makhura said this had not been confirmed."Those who were around claim this was a robbery," said Makhura.The youngsters had allegedly taken cigarettes from Sithole, who was a vendor, and then refused to pay him, Makhura said.He said xenophobic attacks would not be justified or tolerated."We would like to send a strong message that anyone involved in attacks on foreign nationals will be arrested," he said.Makhura later addressed the community, where he called for unity.Meanwhile, Defence Minister Nosiviwe Mapisa-Nqakula was visiting the Alexandra police station. She met the policemen behind close doors.