The Crown Prosecution Service will consider bringing charges against four men arrested on suspicion of murdering missing Claudia Lawrence when a dossier of evidence is completed, police have said.
She disappeared on her way to work in York in March 2009 and there has been no sign of her since.
The four men, in their 50s and from the York area, were arrested earlier this year. They have been released from bail, North Yorkshire Police said.
A file of evidence has yet to be completed for the CPS, which could take some time, and assessment of the case by lawyers may also be lengthy, the force said.
The officer in charge of the inquiry stressed it remained active and urged people not to identify the men in question.
Detective Superintendent Dai Malyn said: "This is to ensure the investigation and legal process are not compromised or potentially damaged in any way.
"This includes naming or publishing images of the men, their home addresses, places of work, their vehicles and properties on traditional media platforms or social networking sites.
"Your co-operation and support is greatly appreciated by the investigation team."
Martin Dales, friend and spokesman for Miss Lawrence's father Peter, said: "Obviously it is pleasing that the investigation is ongoing and has reached this particular point.
"We will wait and see what the CPS come up with when they have had the chance to study the documentation."
Miss Lawrence lived in the Heworth area of York and was 35 when she disappeared.
She was reported missing by her father after concerns were raised when she failed to turn up for her 6am shift at a University of York kitchen.
Police said they believe she was murdered although no body has ever been discovered.
North Yorkshire Police reviewed the case in 2013 following the formation of a new major crime unit, and since then officers have carried out a number of high-profile searches including at her home and an alleyway leading behind it.
Anyone with information that could assist the investigation should contact North Yorkshire Police on 101.