Claudia Lawrence was last seen making her way home from work
The mother of missing chef Claudia Lawrence has pleaded for help to find her daughter, describing the ordeal as "every parent's worst nightmare".
In a police statement, Joan Lawrence said she wanted to make a further appeal to anyone who could help to come forward with any information.
Detectives are now treating the disappearance of Miss Lawrence, 35, who was last seen on 18 March, as murder.
"We are devastated and miss and love her so much," said Mrs Lawrence.
Her daughter was last seen near her home after leaving the University of York's Goodricke College, where she works as a chef.
In her appeal, Mrs Lawrence said: "The situation I find myself in is every parent's worst nightmare.
"Our children, no matter how old they are, are still the most precious things in our lives.
"I am blessed with two beautiful daughters, not only beautiful on the outside, but inside as well.
"I wish to appeal for help to you all, whoever you are.
"The response so far has been fantastic but unfortunately as we speak, our attempts have been unsuccessful in finding Claudia.
"Come forward with any information no matter how insignificant or trivial [you] think it may be."
Miss Lawrence last spoke to her father and mother on the evening of 18 March
At his weekly news conference, Miss Lawrence's father Peter re-appealed for a man who may hold vital information about his daughter's disappearance to get in touch.
Officers want to speak to a man and a woman seen on Melrosegate Bridge at 0535 GMT on Thursday, 19 March.
The couple were seen near an electricity substation on the route which Miss Lawrence normally took to walk to work.
Mr Lawrence, 62, said the man may have a totally innocent explanation, but it was important for him to get in touch.
The man was wearing dark combat trousers and was said to be skinny and was smoking a cigarette with his left hand, which has been described as "unusual".
The woman was said to have mousey hair and was wearing a blue jacket.
Police said they did not know if it was Miss Lawrence but described it as a "significant sighting".
Mr Lawrence said: "Somebody else must know who that [man] is from the description; husband, partner, brother, neighbour, workmate.
"We really need to know, even if it is just to eliminate."
Crimestoppers has put up a £10,000 reward in connection with the investigation.