Detectives hunting the killer of park jogger Margaret Muller say she, or a woman who looked like her, was seen with a man at the time of the murder.

If the woman was the 27-year-old murder victim then it is a "significant new lead", said Detective Chief Superintendent John Shatford.

The American artist was stabbed to death in Victoria Park, Tower Hamlets, east London on Monday.

Mr Shatford said her parents would be arriving from the United States on Friday and would visit the murder scene.

The victim lived in a converted factory block

"There has been a sighting in the park on the morning that Margaret was killed of a young lady fitting her description, in that she was wearing a green fleece similar to Margaret's," Mr Shatford said.

"At one stage she was seen to be in company with a man who ran beside her."

He was described as six feet tall, of medium build with dark hair and ginger stubble. He was wearing a yellow-orange running top.

He added Ms Muller had also been seen with a man in the Good Mixer pub in Camden on the night before she died.

He is described as white, 6ft tall, between 30 and 35-years-old of stocky build with a square jaw. He had mousy brown hair waxed into spikes and stubble on his face.

He was wearing a US style T-Shirt and a black leather jacket.

Floral tributes have been left near the murder scene

Police are also still trying to trace two men "of Mediterranean appearance" who were seen running from Victoria Park at the time of the murder.

Police said the pair appeared to check each other's appearance and clothing before resuming at a slow walking pace.

One was described as holding his head down and the witness thought he was trying to hide his face.

Miss Muller, who was 4 ft 10 in tall, had moved to London from the US in 1998 and studied and worked at the Slade School of Fine Art.

Random attack

As a student she supplemented her income by painting and had a studio in a converted factory in Hackney in which she lived.

Police are also speaking to her friends to build up a fuller picture of her life.

They said she had many friends and other artists had come forward to fill out the details of her last days.

Miss Muller may have been murdered in a random attack but detectives are also looking in to where she had been recently, exploring the possibility that she knew her killer.

Dozens of floral tributes have been left near the scene of the murder - many from people who knew the artist.