CRUCIAL witnesses need to come forward to help solve the horrific murder of Jim Attfield.
Detectives are desperate to speak to a couple spotted near Castle Park before the murder of Mr Attfield.
The 33-year-old father-of-five was stabbed 102 times and died shortly after 5.45am on Saturday, March 29, near Lower Castle Park and Guildford Road.
The couple were sitting on a bench by the lake between 11.30pm and 11.40pm on Friday, March 28.
Det Chief Insp Simon Werrett said: "The man is white, tall and of stocky build.
"The only description we have of the woman is that she was white.
"They were sitting at opposite ends of the bench so we do not know for certain if they knew each other, but they may have been a couple who have had a row earlier in the evening and were sitting apart not talking to each other.
"The witness we have spoken to believes that about ten metres away from where this couple were sat there was also a man sat on the grass who was white, aged 30 to 40 and wearing a dark jacket and possibly jeans.
"This may have been Mr Attfield.
"I am keen to speak to these two people so I can eliminate them from the investigation.
"But they may also have vital information.
"I would urge them or anyone who knows who they are to contact my investigation team."
Officers are still trying to find out who killed the student, from East Bay, Colchester, three weeks ago.
A 27-year-old woman from the town was arrested on Friday April 11 in connection with Mr Attfield’s death and is currently on police bail until Thursday April 24 pending further enquiries.
Anyone with information is asked to call Essex Police on 101 or Crimestoppers anonymously on 0800 555111.