A 13-year-old boy has been arrested on suspicion of murdering a mechanic in south-west London.
The teenager is being questioned by police about the death of Martin Thomas in Roehampton on 22 April.
The 39-year-old was found unconscious at his home with stab wounds and died at the scene.
His sister, Vyree Thomas Williams, told the Wandsworth Guardian he had moved to London from Jamaica to make a better life for himself.
“He was a good guy, he was humble,” she said. "He’s not perfect but he was determined to make it.”
A 15-year-old boy, who cannot be named for legal reasons, appeared at the Old Bailey on 29 April charged with murder and was remanded in custody.
Police have arrested and bailed two more boys, aged 17 and 16, in relation to the case.
Detectives continue to appeal for information and are trying to identify three individuals seen in the area before the incident.
Anyone with any information is asked to call the incident room on 020 8721 4205 or Crimestoppers anonymously on 0800 555 111.