Detectives investigating the murder of mum-of-three Rania Alayed have contacted hundreds of motorists to help trace a campervan that could have been used in her disappearance.
In recent weeks officers from Greater Manchester Police, supported by teams from North Yorkshire, have been searching a stretch of the A19 near Thirsk.
As part of the investigation, detectives have established that a white campervan travelled from Manchester to the A19 around the time of her disappearance.
It is believed the vehicle stopped at a layby by the side of the A19 in the early hours of Saturday 8 June 2013.
The exact location of that specific layby is not known and GMP are now seeking help from the public to help them find Rania.
Officers have now sent letters to the keepers of 350 vehicles travelling on the A19 or A168 between the junctions with the A172 and A1(M) between the hours of 3am and 5am on Saturday 8 June 2013.
The letter ask the driver, or anyone travelling in the vehicle, to contact the investigation team if they have any information concerning this white camper van Police believe was parked in a lay-by on the northbound carriageway during this time.
Detective Chief Inspector Peter Marsh, of Greater Manchester Police's Major Incident Team, said:
"I cannot begin to imagine the hurt Rania's family are experiencing knowing she is still missing "Since Rania disappeared in June we have been working tirelessly to find her,and will continue to do so.
"Two people have been charged with her murder and as part of our investigation we are now asking motorists who use this stretch of road to tell us if they saw anything around the 8th June 2013.
"We are hoping to hear from anyone who saw this white campervan and, in particular, if they saw it parked by the side of the road or in a layby.
"I understand there might not be anything unusual about a campervan parked on a layby in the early hours and I recognise it might not have struck you as significant at the time.
"However, we have reason to believe that Rania's body could be located near to this stretch of road and this is where we have been concentrating our searches.
"I am also interested to hear from anyone walking in the area or working who may have seen some suspicious activity or come across any unusual areas of ground such as a disturbance, cut vegetation.
The area in question is in excess of 15 miles long and we have a large amount of ground to cover. "We have been working closely with our colleagues in North Yorkshire Police and have used specialist search equipment supplied by the military to help locate her. "
"As Rania still remains missing it is crucial that we go to the next stage and publically appeal for information.
If you believe you saw Rania after 7pm on 7 June 2013, we are keen to hear from you."
Anyone with information on the movements of this white camper van, should contact the Major Investigation Team on 0161 856 4711.
Two men have previously been charged in connection with Rania's disappearance. Ahmed Khatib of Knutsford Road in Gorton was charged with murder and Muhanned Mahmood Al Khatib, of Arthur Millwood Court, Salford, has been charged with murder and perverting the course of justice.