A man who had reportedly just left jail after being locked up over the murder of an innocent father was stabbed to death on Halloween near a children's playground in south-east London.

Rocky Djelal, 38, was fatally injured in Southwark Park, Rotherhithe, just before 2pm on Wednesday in what detectives believe may have been a targeted attack.

Witnesses described the suspect as a white man aged between 20 and 35 wearing dark clothing underneath a fluorescent hi-vis vest, with a hood covering his face.

Rocky Djelal, 38, (left, in a police mugshot) was fatally injured in Southwark Park, Rotherhithe, just before 2pm on Wednesday in what detectives believe may have been a targeted attack. He had previously been jailed over the murder of Christopher Foster (right)

CCTV images show the lone suspect in the park shortly before the killing before he leaves and re-enters by the Gomm Road entrance, Scotland Yard said.

He then kills the father-of-one before calmly walking away.

Djelal had been released after a six-year prison sentence for conspiracy to cause GBH after the mistaken identity murder of Christopher Foster on Borough High Street, Southwark, in 2013.

The city porter and father-of-one, 34, was stabbed in the back as he smoked a cigarette with a friend outside the St Christopher's Inn and died an hour later after suffering catastrophic internal injuries.

Djelal was charged for murder but had this dropped mid-trial as he and two other defendants agreed to plea conspiracy to commit GBH. Aytach Lisani, 33, confessed to murder and was jailed for life.

In 2008, Djelal was jailed for three years after punching Arsenal and England footballer Sam Kanu, 24, when he tried to stop him stealing bottles of wine from a London Bridge Costcutter. The attack left him in a wheelchair with permanent brain damage.

Witnesses described the suspect as a white man aged between 20 and 35 wearing dark clothing underneath a fluorescent hi-vis vest. Pictured: Southwark Park yesterday

CCTV images from the scene (pictured yesterday) showed a man killing Djelal before calmly walking away, according to police

A friend of Djelal told The Standard yesterday: 'I saw Rocky three days ago and he was fine but he had just got out of jail. I don't think he was working, he used to be a labourer.

'He's got kids, and I wonder if he was in the park with them when he was stabbed. They're going to grow up without a dad now. I'm still in shock.'

A cousin said he had 'turned his life around'.

Detective Chief Inspector Simon Harding said: 'This was a calculated and brazen attack, carried out in broad daylight in the middle of a busy park where children were playing.

'Any speculation about the motive is unhelpful at this early stage, but we do believe that Rocky may have been targeted.'

Djelal had been released from prison over after the mistaken identity murder of Christopher Foster on Borough High Street, Southwark, in 2013.

A post-mortem examination on Mr Djelal, from Rotherhithe, is scheduled for Thursday afternoon.

There have been no arrests.

Police are appealing for witnesses or anyone who has video footage of what happened to get in touch.

The killing is the 115th murder investigation in London this year.