A 52-year-old man was killed at a Butlin’s holiday camp last Friday night after being punched during a bar brawl.
The man, who has yet to be named, hit his head on the floor after being assaulted at the camp in Bognor Regis, West Sussex.
He was taken by ambulance to a hospital in Brighton but died there on Tuesday - four days after the attack.
A 31-year-old man from Wandsworth, south London, had initially been arrested and charged with grievous bodily harm. He was bailed on the initial charge but is expected to be re-arrested now that his victim has died.
Detective Chief Inspector Andy Wolstenholme of Sussex police said: “A fight at a holiday park, which involved several people, sadly resulted in the death of a man.
“The bar was very busy at the time of the assault and we believe many of those present would have witnessed the assault and the aftermath.
“We have spoken to some witnesses who were present at the time, but we would be keen to speak to anyone who hasn’t yet made contact with us.
“We arrested a man immediately after the assault and inquiries are ongoing,” he added.
A Butlin’s spokesman said: “We are very saddened to hear this terrible news and our thoughts are with the victim’s family and friends.
“We have offered our full assistance to the Police in their enquiries throughout the investigation and will continue to do so.”
The Bognor resort was one of the three original resorts where Butlin’s was first established and the firm recently invested £40m in it, including building a state-of-the-art swimming pool.