She was Michelle Martin, 48, from Moffat.
She was found seriously injured on the A701 in the early hours of Saturday June 18.
Officers said the indications were that she had fallen from a moving vehicle at about 1.45 am.
Emergency services attended and Michelle was taken to Dumfries and Galloway Royal Infirmary, where she later died last Thursday, June 23.
A report has been submitted to the Procurator Fiscal.
Detective Inspector Graeme Robertson, of Dumfries CID, said: “Our thoughts are with Michelle’s family and friends at this difficult time.
“Our enquiries are ongoing to establish the full circumstances and I would urge anyone with information, who has not yet spoken to police, to get in touch.
“Anyone with information should contact police Scotland via 101, quoting incident number 0336 of 18 June.”