The brother of a tax specialist killed during a night out celebrating a promotion has made a fresh appeal for witnesses as he carries out a vigil on the 20th anniversary of his brother’s death.

Jay Abatan, who worked for PricewaterhouseCoopers in London, died after he was attacked outside the Ocean Rooms in Brighton in January 1999.

The 42-year-old hit his head on the pavement during the incident and died five days later in hospital.

Charges of manslaughter against two men were dropped because of insufficient evidence and Sussex Police were criticised over the handling of the investigation into the death of the father-of-two.

Michael Abatan, a 51-year-old lead systems analyst for NBCUniversal, marked two decades without his brother by holding a vigil outside Brighton Police Station.

He said: “Jay was a decent person, a hard-working, intelligent man with a lot to look forward to. His future was cut short on the night he was celebrating his promotion at work.

“We know there are witnesses still out there that haven’t come forward, witnesses that are still struggling with their conscience and who are frightened. We want them to have the courage and come forward.”

Abatan said he believed the attack was racially motivated. The siblings are of mixed race, with a British mother and Nigerian father.

Abatan said he had not been notified of any new developments by Sussex Police.

He added: “Despite two investigations and reviews by other police forces, there are still witnesses out there who have never been spoken to. This fills me with despair.”

Assistant Chief Constable Nick May said: “Sussex Police has accepted that mistakes were made during the initial investigation into the unlawful killing of Jay Abatan, and regret that nobody has been convicted of this cowardly attack.

“We have apologised publicly for the failings in 1999 but reinforce that current investigative practices are vastly different.”

May said the force “remains committed to investigating any significant new information that will assist in convicting those responsible for Jay’s death”.

“Senior detectives have met and corresponded with the Abatan family on a number of occasions over the years in order to respond to their concerns and to provide answers to any questions raised,” he added.

“The last of these meetings was in March 2015 with the police and crime commissioner Katy Bourne.

“The initial investigation into Mr Abatan’s death has been subject to considerable, well-documented scrutiny.

“Its shortcomings, for which former chief constable Joe Edwards personally apologised to Jay’s family in 2005, were highlighted in an independent review that resulted in the second investigation and review.

“At their request the family were provided with a detailed account of this investigation.”

The police chief said the force had completely updated and reorganised the way it investigates both major crime and critical incidents since 1999.

“Significant changes to our investigative practices include a dedicated Major Crime Team, accredited senior investigating officers and trained family liaison officers,” he added.