Frankie Boorman, 53, was found collapsed in Pelham Street, at the junction with Harold Place, shortly before 8pm on April 10.
He was taken to hospital where he died on April 22.
Police said there was evidence Frankie had been assaulted in nearby Wellington Place prior and a 35-year-old man was arrested. He was released under investigation while enquiries continue.
A post-mortem examination determined the assault was unlikely to be linked to Frankie’s death but further investigation is being carried out.
Police want to speak to potential witnesses seen on CCTV in the area to find out what caused Frankie to collapse, including the possibility there was another assault leading to his collapse.
Detective Inspector Duncan Elliott said: “Frankie was a popular character who spent a lot of time in Hastings town centre. He was well-loved by his family and friends and our thoughts are with them at this difficult time.
“Frankie’s family are desperate to find out what happened to him, and we are conducting numerous enquiries to help provide them with those answers.
“The people in these pictures were in the vicinity of Pelham Street and Harold Place around the relevant time and could be key witnesses. We’d urge them to please get in touch with us to help support our ongoing investigation.”
Any of the people in these pictures, or anyone who recognises them, is asked to contact police at https://mipp.police.uk/operation/4721F19-PO1.
Information can also be passed to police online or by calling 101 quoting Operation Canford. Or contact Crimestoppers anonymously on 0800 555 111.
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Police investigating the sudden death of a man in Hastings are looking to identify a number of potential witnesses. Photo: Jpress
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Picture one shows a person who walked from the direction of Havelock Road, stopped for a short moment outside Jempson’s Café near Pelham Street, and then walked along Wellington Place towards McDonald’s. Photo: Police
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Picture two shows a person who rode a skateboard from the direction of Havelock Road, across the pedestrianised area of the town centre and towards Pelham Street. Photo: police
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Picture three shows two people who walked from the direction of Queens Road, across the main pedestrianised area of the town centre and then through the subway that runs between Harold Place and the beach. Photo: police