Jodi was found on 30 June

Detectives said the information, which came from two independent witnesses, was a "significant development".

A girl matching Jodi's description was seen walking towards the entrance to the Roman Dyke pathway on the outskirts of Dalkeith at about 1700 BST on 30 June.

The witnesses also saw a man walking closely behind the 14-year-old.

Detective Inspector Tom Martin said one person also believed that he saw the man on the night of the police reconstruction a week later.

"If this is the case we need to trace this person as a matter of urgency as he may have seen something important on the night that Jodi died," he said.

Knife attack

Jodi's partially clothed and mutilated body was found on the Roman Dyke path on 30 June.

She had been the victim of a frenzied knife attack.

The teenager had left her family home at about 1700 BST to walk to her boyfriend's house but the alarm was raised later when she failed to get there or return home.

The man seen walking behind this girl could be a crucial witness and was seen again a week later meeting two friends Detective Inspector Tom Martin

Mr Martin said the man who had been seen by the witnesses on the night Jodi was killed was in his late teens or early 20s.

He was white, of stocky build, between 5ft7in and 5ft10in tall, with short brown/ginger hair.

He was wearing a dark coloured sweatshirt top, possibly with a hood, and dark trousers.

He may also have been carrying a backpack on his shoulder.

One of the witnesses thought he saw the same man again in the same area a week later as police staged a reconstruction of Jodi's final movements.

"This leads police to think he may be a local person who uses the route fairly regularly," said a spokesperson for the Lothian and Borders force.

Met friends

On 7 July the man was seen at about 1800 BST walking in Morris Road on the way to Easthouses Road.

He met two friends of roughly the same age, who gave each other a "high-five" style greeting before pulling each other into a hug.

One of the friends was on a bike and wearing shorts, while the other appeared to be carrying a videotape.

A reconstruction was held a week after Jodi's death

Mr Martin said: "This information is important and it is very helpful that we have two independent witnesses who saw a girl fitting Jodi's description at a time when we might have expected Jodi to be in that area.

"The man seen walking behind this girl could be a crucial witness and was seen again a week later meeting two friends."

He urged the man, or his friends, to come forward.

"If you think you know who any of these people may be please call the police," he added.