Updated: KEY clues have emerged in the hunt for Claudia Lawrence, as the detective leading the investigation says he “fervently hopes” the missing chef is still alive.

Meanwhile, Claudia’s father, Peter Lawrence, was making a live appearance on ITV’s This Morning show today in another desperate appeal for information.

Police have revealed two new witnesses have come forward, including a woman who spotted two unknown men trying the handle of the 35-year-old’s front door in the week before she vanished.

The second witness was a motorist who saw a man and a woman arguing near to a parked vehicle in University Road, only minutes after she was due to start work at the University of York’s Roger Kirk Centre.

Detective Superintendent Ray Galloway said the quarrelling couple were seen near the roundabout leading to the water tower at Siwards How at 6.10am on Thursday, March 19.

He said the front passenger door of the vehicle was open and the couple were standing on the opposite side of the road to the vehicle.

“It wasn’t a violent confrontation and we don’t know what the man and woman looked like,” said Det Supt Galloway.

“As the witness looked in his rear view mirror he believes the man was stood above the woman as if he is on some form of bank. I have always believed that Claudia has gone with somebody she knows.

“The fact that the passenger door is open suggests that somebody has already been in that vehicle and a subsequent altercation has taken place.

“But I’d like to stress that we don’t know if the woman was Claudia. I would like to identify who these people are and I would appeal to them to come forward. This is a significant line of inquiry that we want to pursue, as it is a key morning in terms of this investigation.

“It is now four weeks since Claudia didn’t turn up for work and obviously as each day goes by my concern for Claudia’s safety amplifies.

“I fervently hope Claudia is still alive, but I have significant concerns.”

Det Supt Galloway also appealed for information about two men seen loitering outside Claudia’s terraced home, in Heworth Road, around five days before she vanished without trace.

He said on either March 10 or 13, a female driver stuck in traffic saw two nervous-looking men at Claudia’s front door in the early afternoon.

“One of the men, an Asian male, appeared to try the door – whether with a key or whether he just tried the door handle, we don’t know,” said Det Sup Galloway. “They were watched by the witness for three or four minutes, as she approached the roundabout at Malton Road.

“There could have been a legitimate reason, we don’t know, and I would appeal to these men to come forward.

“If they were salesmen or there was any other reason why they were there, please come forward.”

The Asian man is described as being in his early 20s, 5ft 8ins tall, of slim build, with a thin pointed nose and dark areas under his eyes. The second man is described as taller, with short dark hair and a heavier build. He was wearing a Crombie-style coat.

Claudia, who has an older sister, Ali, was last seen returning to her home on Wednesday, March 18, at about 3.10pm.

Later on, she chatted happily to both her parents on the phone and sent text messages to various friends – but she has not been in contact with friends or family since 8.23pm that night.

If you have information, phone North Yorkshire Police on 0845 60 60 247 or phone Crimestoppers on 0800 555 111.