Police in Kirkcudbright want to speak to the owner of a silver Rover or MG seen in the St Mary's Isle area of the town on around 11pm on Saturday night.
The appeal comes after a 23 year-old man was assaulted there an altercation at a festival.
He is in a stable condition in hospital.
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49-year-old Callum Phillips was driving at speeds of up to 73mph shortly before the collision which killed 39-year-old Ryan Baird.
Local businesses have been working overnight to move chiller units into the school to cool classrooms down for students taking GCSEs.
Lee Clayton was caught as he tried to deal class A substances to an undercover security officer at the music festival in July last year.