A 26-year-old man [C] was arrested on suspicion of murder this morning, Sunday, 14 August in Surrey and remains in custody at an east London police station.
Police were called at approximately 22:35hrs on Friday, 29 July, to reports of a stabbing near Bethnal Green Underground Station.
Officers and the London Ambulance Service attended and Luther was found collapsed on the forecourt of a petrol station at the junction of Old Ford Road and Cambridge Heath Road, E2.
He was taken by ambulance to an east London hospital where he was pronounced dead at around 23:40hrs.
A post-mortem examination held at Poplar Mortuary on 1 August gave the cause of death as a stab wound to the heart.
Detectives from the Homicide and Major Crime Command are investigating.
Luther, who was 31 years old, had been at a boxing event held at York Hall on Old Ford Road on Friday night. He had become involved in an altercation inside York Hall and was then attacked by numerous people as he left the venue.
A 31-year-old man [A] and a 23-year-old man [B] previously arrested on suspicion of murder have both have been bailed to return in late September, pending further enquiries.
Detectives are keeping an open mind as regards any motive at this stage and are appealing for any witnesses to the incident to come forward.
Any witnesses or anyone with any information should call the incident room on 020 8345 3715. To give information anonymously, call Crimestoppers on 0800 555 111 or email via Crimestoppers-uk.org.