Murder squad detectives are searching for the body of a mother of three believed dumped along a rural stretch of road.
Officers have now traced a suspect white camper van spotted driving along the A168/A19 near Thirsk at the time 25-year-old Rania Alayed went missing.
But detectives do not yet know exactly where the van stopped and the stretch of road near Thirsk, North Yorkshire, runs for 19 miles with numerous laybys.
Ms Alayed's body is still missing but two men have been charged with her murder.
Officers want the public's help in trying to pin down exactly where the camper van was seen as today they continued searching along the A-road.
Teams of officers from Greater Manchester Police (GMP) and North Yorkshire Police carried out a line search today in a northbound layby between the A1 and Thirsk and searches will continue on this stretch of road for a number of days or weeks, police said.
Ms Alayed was reported missing from her home in Cheetham Hill, Manchester, on July 2, having been last seen in public on the evening of 7 June.
She had previously lived in Norton, Stockton-On-Tees, and moved to Manchester in January.
Her disappearance was described by police as "extremely out of character".
It is thought she was taken in a white camper van in the early hours of June 8 to the Thirsk area of North Yorkshire, where her body was disposed of.
As part of the investigation, detectives established that a white camper van 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, but the exact location is still not known.
Police have 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 asks the driver, or anyone travelling in the vehicle, to contact the investigation team if they have any information concerning the white camper van.
Detectives believe it was parked in a lay-by on the northbound carriageway during this time.
Detective superintendent Serena Kennedy, of GMP said: "Today's search is one of a number that have been carried out in recent weeks.
"GMP, supported by colleagues from North Yorkshire Police and the military, have been working tirelessly to find Rania and we will not stop until we can find her.
"We are also continuing to appeal to anyone who saw this white camper van and, in particular, if they saw it parked by the side of the road or in a layby.
"I would also like to thank the public for their tremendous response to this so far.
"I understand there might not be anything unusual about a camper van 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.
"If you believe you saw Rania after 7pm on 7 June 2013, we are keen to hear from you."
The Independent Police Complaints Commission (IPCC) is investigating how GMP dealt with previous contact with Ms Alayed, who reported being a victim of domestic violence.
Ahmed Khatib, 33, of Knutsford Road in Gorton, Manchester is charged with murder and Muhanned Mahmood Al Khatib, 38, of Arthur Millwood Court, Salford, has been charged with murder and perverting the course of justice.