The CCTV images are from Valley Gardens in Pontefract and were taken at about 1am and 3.40am on September 18 - the date that Simon Hailes was found with head injuries at an address in Dark Lane.
Mr Hailes, who was 40 and from the Kidderminster area of Worcestershire, died of his injuries at Pinderfields Hospital a week later.
Detective Inspector Phil Davis, of the Homicide and Major Enquiry Team, said: “We are continuing to investigate the full circumstances surrounding the death of Mr Hailes.
“Our enquiries suggest Mr Hailes was in the area around the time these images were taken and we are keen to identify this person, who we believe to be a male, as it is possible they may have witnessed something that will assist our investigation.”
Two people arrested on suspicion of assault in connection with the incident remain under investigation pending further enquiries.
Anyone with information about the incident is asked to contact police by calling 101, or online via www.westyorkshire.police.uk/101livechat, quoting reference 285 of 18/9.
Alternatively, call independent charity Crimestoppers anonymously on 0800 555 111.