A van was stolen while its driver made a delivery.
A white Transit van, with a 68 registration plate, was stolen from Marsh House Avenue and Braemar Road area of Billingham between 11am and 2pm.
The vehicle was later found abandoned in the town's Blakeston Court.
Police are linking the theft to a similar incident 24 hours earlier when a white Ford Transit van, again with a 68 registration plate, was stolen from Dunlin Close, Stockton, as the driver delivered a parcel at 1.20pm.
The vehicle is believed to have been driven to the Norton area before packages were transferred to a silver van and the stolen vehicle was abandoned on Bolsover Road, Norton, sometime before 1.55pm the same day.
Any witnesses or anyone with information regarding these incidents is asked to contact Detective Constable Matt Brophy, from Stockton Operational Crime Team, on the non-emergency number 101, quoting event number 225688 and 226272.
Independent charity Crimestoppers can be contacted anonymously on 0800 555 111 or www.crimestoppers-uk.org.