It seems they're now trying to link her disappearance to Christopher Halliwell :
Christopher Halliwell's could be linked to Claudia Lawrence's murder claims her father | Daily Mail Online
Interesting theory, the man is evil and his parents apparently lived a short distance away from her in York (so he knew the area). If I were the cops, I'd be dragging sonar equipment over both of the fields his 2 known victims were found in !
Lawrence disappeared on the 19th March as did Linda Razzell and as did Sian O'Callaghan. Halliwell was convicted of murder for Sian. He did building work at the home of Razzell, her body has never been found and her husband has served 14 years for a crime he swears to this day he did not committ.
The 19th march was a special day for Halliwell (I think a partner ditched him) he's been convicted of murdering one person on that day and it's entirely conceivable Lawrence and Razzell were his victims also.