South Yorkshire Police are appealing for help from the public in identifying two witnesses into the assault of 39 year old John Methley that led to his death.
Mr Methley was assaulted by two men at 6.23pm on Monday 4 February on the Midland Road roundabout. He was left unconscious with serious injuries to his head.
He never regained consciousness and died as a result of the trauma six days later.
Officers are keen to speak to a man and woman who they believe were in the area at the time Mr Methley was assaulted.
CCTV images have been released to help identify the potential witnesses.
The woman in the images appears to be wearing a jacket with a fur hood, a skirt and knee high boots, carrying a large, dark-coloured handbag.
She is believed to have been walking from Wortley Road towards Midland roundabout before stopping to speak to a man.
The man in the images appears to walk from Midland Road towards Midland roundabout on his mobile phone before stopping to speak to the woman.