Officers searching for Dr Peter Coshan’s remains have appealed for information about a car they say could be involved in his disappearance from Edinburgh earlier this month. Senior Police Scotland officers believe the 75-year-old body was dumped either in the Scottish Borders or Northumberland. He was last seen alive in Edinburgh’s Leith district on Thursday, August 11. Police are seeking any sightings of a dark Vauxhall Vectra car, which has been described as ‘central to the investigation’. The 57-plate car is understood to have been in the area overnight on Monday August 15 into Tuesday. Detective Superintendent Andrew Patrick said: "This is obviously a very distressing time for Peter's family and our priority is to find him. "I am therefore seeking the public’s help in trying to find Peter's body. "Extensive enquiries have been carried out which had led us to explore this area. "I am appealing for anyone who may have been in the Scottish Borders and Northumberland, including travelling on the A7, the A68 or any others roads in these areas, during the hours of darkness on either Monday, 15 August, 2022 and Tuesday, 16 August, 2022. "That evening and early morning was the end of the very hot weather we had, and a warning for thunderstorms was issued. I would ask anyone who may have been in these areas to think back to that time, you may remember it due to the unusual hot weather and thunderstorms. "I believe the areas of the Scottish Borders and Northumberland are key to helping us find Peter, so please take time to think back and consider if you saw a 57 plate dark coloured Vauxhall Vectra in and around those areas.” He added: "I am also keen to speak to anyone who travels in these areas regularly and has a dash cam. "Please check the footage as it may have captured something which could prove vital to our ongoing enquiries to locate Peter." Dr Coshan taught biology at Fettes College in Edinburgh between 1972 and 2005 and ran its Duke of Edinburgh Awards scheme for 33 years. The exclusive school counts ex Prime Minister Tony Blair as one of its former pupils. Detectives are seeking specific sightings of the Vauxhall so they carry out a more systematic search. They have set up a website that gives members of the public access to a form to send information directly to the Major Investigation Team and allows any contact to remain anonymous. submitting information. The portal can be accessed at: https://mipp.police.uk/operation/SCOT22S27-PO1 Mr Coshan was last seen in the Seafield Road area of Leith, Edinburgh around 11.50pm on Thursday, 11 August, 2022 and was reported missing the next day. Anyone with information is asked to call Police Scotland on 101 quoting incident number 1745 of 12 August, 2022 or the charity Crimestoppers on 0800 555 111. Paul Black, 63, and Paul McNaughton, 27, were remanded in custody last week after they made no plea at Edinburgh Sheriff Court to a charge that they murdered Mr Coshan, in Edinburgh, on August 11 2022.