Detectives investigating the murder of James 'Jim' Attfield in Lower Castle Park in Colchester want to trace a woman he spoke to on Facebook days before he was stabbed to death.
The victim, described as vulnerable, was knifed more than 100 times before his body was found on March 29.
Efforts to find his killer have so far come up short and Essex Police detectives have been reviewing his Facebook account, Jim.Attfield.
Detective Superintendent Steve Worron, of the Kent and Essex Serious Crime Directorate, said: "It appears he may have been in contact with a woman who went on holiday around the time of Friday, March 21 and was due back on the Saturday that he was killed.
"From posts James made on his page it is believed the woman likes dancing, pottery and may have sung karaoke with him.
"We would like this woman to contact the investigation team so she can tell us about her knowledge of James. Also if anyone was friends with James on Facebook and they haven't yet spoken to police officers please get in touch as we would like to speak to them."
Police are also continuing the investigation into the murder of Nahid Almanea, fatally attacked on the Salary Brook Trail on June 17. It is being run parallel with the Attfield probe.
There are a number of possible witnesses to both murders that have been asked to identify themselves to the police but they have not yet made contact with Essex Police.
In relation to James' murder, detectives still want to trace a man and woman seen sitting on a bench in Lower Castle Park on the night before James died.
Det Supt Worron said: "The man and woman we would like to speak to were seen sitting on a bench in Lower Castle Park, near to where James was found.
"They were spotted at 11.30pm on Friday, March 28, sitting at opposite ends of the bench, near a man who was sitting on the grass.
"It is unknown whether they knew each other, but they may have been a couple who had an argument earlier in the evening and so were sitting apart, not talking to each other.
The man was white and is of a stocky build. The woman is described as white. They need to contact us. It may be embarrassing or difficult for them to call but a man has died and it is vital they come forward."
