Takayo Nembhard, 21, died after being stabbed at around 8pm on Monday 29 August while attending the Notting Hill Carnival, west London.

The rapper, from Bristol, was taken from Ladbroke Grove, under the Westway flyover, to hospital where he was later pronounced dead. A post-mortem examination showed he died from a stab wound to the right groin femoral artery.

Officers have already arrested three men and a woman, but have now launched an appeal to identify a fifth person caught on CCTV footage.

Detective Inspector Laura Semple, of the Specialist Crime unit, said: "We are making good progress with our investigation into Takayo's tragic death which has naturally left his family devastated.

"However, we really need the public's help to tell us who this person is in the CCTV image we have issued today and anyone with information - no matter how small - about the murder to come forward.

"If you can help please get in touch immediately."

Mr Nembhard was an up-and-coming rap and drill artist known as TKorStretch, with thousands of views on social media. He left behind a girlfriend and son, who was born earlier this month.

In a statement, his family said: "Takayo's death has left a painful ache for all who loved him and still love him.

"He was so looking forward to being a dad and would have made a fabulous one as he came from a strong family unit. His son was born on 9 November and although this should have been a happy occasion, it was bittersweet. Our family, which includes his girlfriend, continue to struggle with coping without him on a daily basis.

"Our family beg the public to provide any info they may have, be that videos or photos that were taken on 29 August in the Ladbroke Grove area.

"Please help us to bring Takayo's killers to justice and therefore some comfort to us knowing he didn't die in vain."

Detectives believe there were many witnesses to the murder due to the number of people in the immediate area, and are keen to hear from anyone with information, including anyone who was filming or photographing at the time and may have captured relevant footage or images.

A dedicated page, set up on the Metropolitan Police's website so witnesses can upload photos and videos of the incident, can be accessed at mipp.police.uk/operation/01MPS22U27-PO1.

Information can also be provided by calling the incident room directly on 020 7175 2206 to speak to an officer, by calling 101, or by tweeting @MetCC quoting 7478/29AUG.

Anyone wishing to remain anonymous can contact the independent charity Crimestoppers by calling 0800 555 111 or by visiting its website. Call-handlers never ask for personal information and do not track devices.

On 19 October, a 23-year-old man and an 18-year-old man were arrested in Bristol on suspicion of murder, while a 20-year-old woman was arrested in Islington, north London on suspicion of assisting an offender.

The 18-year-old man and the woman have since been bailed pending further enquiries, while the 23-year-old man has been released under investigation.

A 17-year-old male was also arrested in Bristol on 22 October on suspicion of murder and has been bailed pending further enquiries.