A man who died after a fight on a train, sparking a murder investigation, phoned his mum the night before in tears.

Warsame Warsame, known as Sammy, was found unconscious on a train at Raynes Park station on Saturday, on the 1.16pm Waterloo to Chessington service.

He died two days later in St George’s Hospital after falling into a coma.

Police are investigating whether he died of injuries sustained in the fight – which took place about 45 minutes earlier on a different train between Raynes Park and Wimbledon – or if it was caused by a pre-existing medical condition.

Mr Warsame, 24, needed regular dialysis ever since he was bottled repeatedly inside a Kingston nightclub in 2007.

Referring to the phone call, his mother Basra Warsame, from Gloucester Road, Norbiton, said: “All he was saying was ‘I’m sorry, I’m sorry, forgive me’. He said it six times. Then the telephone went dead.”

Mr Warsame, a music-loving rapper who used the name DJ Instant, was living at Surbiton YMCA at the time of his death.

Police were also examining CCTV yesterday.

Detective Superintendent Gary Richardson said: “What we know at this stage is Sammy was involved in an incident before he died, and while we work to establish the cause of death we are appealing for anyone with information to come forward.”

Call British Transport Police on 0800 405040 or Crimestoppers, anonymously, on 0800 555 111.

Former Raynes Park High School pupil Warsame Warsame had shown his support on Facebook for a teenager attacked randomly by a soldier and left with permanent brain damage.

He “liked” a page supporting 15-year-old Mo Bourner, who was attacked in October 2011 in Bexhill and left permanently disabled. Two men were jailed for the attack in July.

His sister Deqa, 27, said: “We are very unsure what happened.

“He was found unconscious with no shirt, no jacket, no phone, no wallet and no keys.

“There is a lot of suspicion, but we don’t know any more than that.

“He was a happy-go-lucky guy, a positive person, with a really quick-witted sense of humour.

“He was friendly, and a very strong person. He saw a lot in his life with all his health problems, but he was a very talented lyricist and a great brother to all of us.

“He will be incredibly missed. It hasn’t really hit home yet.

“He has been in a coma before. He was attacked in a nightclub in 2007. We had been told he was not going to make it before, but he recovered from that.”

One of Mr Warsame’s four brothers Mohammed Warsame, then 19, was jailed in July 2011 for three years for his role in a bungled town centre security van robbery outside RBS Kingston, along with Stevey Mackay, 19.

His cousin, who asked not to be named, said Warsame had not had any brushes with the law.

He said: “He was like everyone’s little brother.   

He got attacked in a Kingston nightclub years ago. He never recovered from that.

“Some drunk guy laid into him. He got bottled repeatedly. He is not a violent man.

“He had been through a lot and picked himself up and moved on. Eventually he was going to get a kidney.
 

“We want people to come forward with any information.”
 

He said Muslim tradition demanded a quick burial, but the police investigation had caused further anguish for the family by delaying.
 

Richard James, chief executive of the YMCA London South West, said:

“Sammy was a popular resident who will be sadly missed by all at YMCA Surbiton.
 

“Our thoughts and prayers are with his family and friends at this sad time.”
 

An area of the hostel had been set aside for former friends to light candles to remember him, he said.