Police officers arrested two further people yesterday in connection with the murder of 19-year-old Nicholas Robinson in Bristol.
A 43-year-old woman and a 50-year-old man were arrested in Bristol on suspicion of assisting an offender. They are both in custody for questioning.
A 19-year-old man from Bristol and a 48-year-old woman from north London, both arrested on Wednesday on suspicion of assisting an offender, have been released on bail.
Mr Robinson is reported to have been stabbed in a communal stairwell within Ron Jones House in Jamaica Street on March 5. He ran into a communal car park in Lower Gay Street where he later died from his injuries.
Senior Investigating Officer Detective Chief Inspector Andy Bevan said: "I would urge those with information on who is responsible for killing Nicholas, to phone."