The news comes after the 61-year-old man was found injured at the side of the A85 at Kirkton near Taynuilt, Argyll and Bute, in the early hours of Sunday.
Police were alerted at around 1am and emergency services attended, however, the man was pronounced dead at the scene.
Signed diversions are in place via the A819, A83 and A816 as the road remains closed to allow for police to conduct enquiries at the location.
It is anticipated that this will add around 85 miles to motorists’ journeys.
Police Scotland have also been carrying out door-to-door enquiries and are checking for any public and private CCTV footage which could assist in the inquiry.
Anyone with information is asked to call Police Scotland via 101, quoting incident number 0293 of 10 October, 2021.