The sketches from the Royal Engineers Museum were within the silver Ford Transit when it was stolen from Heron Square in the Deans area of Livingston in West Lothian, Scotland, at about 11.30pm on 19 November.
The vehicle – with the registration SG16 SUF – was found in the Ratho area the following day, where it had been stripped of parts and set on fire.
Police Scotland said a man wearing a face covering was seen entering the van and driving eastbound on the A89 towards Newbridge, near Ratho, shortly after the van was stolen.
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Constable Teri McEwan said: “We’re conducting extensive enquiries into this incident and officers are working their way through CCTV and visiting nearby properties.
“I am now asking anyone with information, or anyone who saw someone acting suspiciously in the area around the time, to get in touch with us.
“If you have private CCTV, doorbell or dashcam footage, please also review this and bring anything which may assist the investigation to our attention.”
