The detective leading the hunt for missing Claudia Lawrence revealed that he could have "potentially" spoken to her killer, as her friends and family marked the second anniversary of her disappearance.
Detective Superintendent Ray Galloway was speaking two years after Miss Lawrence was last spotted on a CCTV camera near her home in York and had contact with her family.
The chef, who would now be 37, was last seen on March 18, 2009 near her home in Heworth, York. She never turned up for work the next morning in the kitchen at York University.
North Yorkshire Police launched a huge inquiry which was subsequently scaled back. Detectives have said repeatedly they believe Miss Lawrence has been murdered and that the key to the inquiry is her relationships with a number of men - relationships police have described as having an "element of complexity and mystery to them".
Asked if it was possible that he could have spoken to Miss Lawrence's killer as part of his inquiries into her past, Mr Galloway said: "There is a real potential that we have."
He said there were no specific suspects, but he said there were individuals he needed more information about and he appealed for people who had concerns or suspicions about someone to come forward.
Commenting on the lengthy investigation, he added: "It haunts me. I think about Claudia. I think about the investigation day in, day out. I think people expect me to continue working. I work on behalf of Claudia's family and on behalf of the greater community. Until Claudia's killer is brought to justice there is a danger and we need to resolve it."
Meanwhile, Claudia's father spoke of his family's anguish as he visited York University on Friday.
Mr Lawrence said: "Being here is obviously an extremely poignant occasion for me, particularly because today is two years to the day since Claudia disappeared and two years to the day since I went to her house in Heworth. She has obviously not been seen since. No one has heard from her and we still do not know what happened to her.
"The family are obviously distraught by this and have been for the past two years. It doesn't get any easier as time goes on. In fact, in some ways it gets worse because of the length of time of not knowing what has happened to Claudia.
