DETECTIVES are renewing appeals for information today four weeks after Nahid Al-Manea was murdered.
Det Chief Supt Steve Worron said: "We are trying to build up a clearer picture of who may have been using the Trail on the morning on Tuesday, June 17.
"There are currently around 100 detectives from across the region working to solve both the murder of Nahid and the murder of James Attfield.
"Colleagues have come from Kent, the Metropolitan Police, Suffolk and Norfolk to assist our teams. We are grateful for their assistance.
"We also have a team of officers in Saudi Arabia who are offering support to Nahid’s family.
"This is so they know we are doing everything we can to bring justice for their daughter.
"We are continuing to appeal for information from the public to find witnesses who may be able to help us.
"In particular would like to speak to a man who was seen on the Salary Brook Trail between 10.20am and 10.40am, shortly before Nahid was found.
"He is thought to have been wearing a very distinctive jacket. It is described as being an Italian designer item, it was slightly longer than waist-length, had brown buttons up the front and two pockets also with buttons.
"It was beige in colour, and had a belt which may or may not have had a buckle.
"He was walking on the footpath near the underpass on the A133 side of the Salary Brook Trail. He has still not yet come forward and we urgently need to speak with him."
This is one of a number of appeals for help from the public while the investigation continues.
A decision has also been made to continue high visibility patrols in Colchester
More than 2,500 exhibits including more than 50 knives were recovered from both areas with results coming back daily.
Det Chief Supt Steve Worron said he cannot be sure any are the murder weapon and he, and the teams of more than 100 detectives, are busy going through what they have got.
Nahid Al-Manea, 31, of Woodrow Way, Colchester, was stabbed 16 times and killed on the trail just before 10.40am on Tuesday, June 17.
The Saudi Arabian student was studying at Essex University and walking towards the university when she was attacked.
Father-of-five Jim Attfield, 33, of East Bay, Colchester, was stabbed 102 times and killed on a path between Castle Park and Guildford Road.
He was found shortly before 6am on Saturday, March 29.
Four people remain on bail after being arrested in connection with the Jim Attfield murder.
Detectives believe the killer or killers are still on the loose.
Anyone with information call 01245 282103 or Crimestoppers on 0800 555111.
A £10,000 reward for information leading to the conviction of either killer is still on offer from Crimestoppers.