The first arrest in the five-year-long hunt for York cook Claudia Lawrence is the result of a painstaking review of the investigation into her disappearance.
Senior detectives have made her suspected murder one of their main priorities for 2014 - no force likes to have unsolved suspected murders on its books and North Yorkshire has two from recent years.
The mystery of what happened to Ms Lawrence in 2009 and the whereabouts of 38-year-old Marsha Wray, who vanished from her Harrogate home in 1987, were both made the subject of cold case reviews last year.
Claudia s disappearance was the focus of a massive police investigation from the day it was realised she had vanished, leaving behind her family, friends, bank cards and passport - but detectives have found no trace of her.
The fact that no arrests were made despite a significant number of so-called persons of interest being identified - some of whom were men she had had relationships with - was an indication of how the investigation struggled.
The review team, led by Detective Superintendent Dai Malyn and overseen by head of crime Chief Superintendent Simon Mason, has a wealth of information to go on: reams of interviews, witness statements going back more than five years and forensic evidence that had been carefully filed away.
A new team of scenes of crime specialists spent weeks re-examining Ms Lawrence s terraced home in the hope some new forensic evidence might be found that would give them a new lead.
But detectives know that existing files are most likely to hold the key to unlocking this case: a statement that can now be disproved; a question not answered that can now be shown to be significant; or something overlooked, wrongly categorised or missed altogether.
Ms Lawrence s mother Joan has spoken at length to Det Supt Malyn and thinks his review could bring her the answers she wants.
I think if they don t (solve the case) they will have tried their utmost, she told me.
They re working so hard on it. I don t think they ll easily give up.
Announcing this first arrest, of a man named locally as Michael Snelling, 59, North Yorkshire Police issued a warning to those in their sights.
Police cannot rule out the possibility of further arrests in the future as the review continues, they said.
After five years and two months, the investigation is far from over.