Police say the man, who's not yet been named, died at around 6.40pm on 18 September.
Police say the 66-year-old died in a single vehicle accident on the track to Fort Clonque, at Alderney's south-western tip.
They say as investigations are carried out there will be a police presence in the area and ask people to stay away.
Police looking for person in connection with Northside Chip Shop damage
Guernsey Police have released an image of a person they would like to speak to about an attack on Northside Chip Shop.
Guernsey passengers can book ferries from next Tuesday
Bookings for ferry sailings from Guernsey from late March 2025 will go on sale next Tuesday (26 November) following approval of Brittany Ferries and Condor's new 15 year contract.
Car fires to floods: Guernsey Fire and Rescue attend 24 bad weather incidents
Fires, floods and flying roof tiles... Guernsey Fire and Rescue dealt with an 'unprecedented number of incidents' yesterday morning (21 November).
Aurigny takes delivery of fifth ATR
Guernsey's States-owned airline has confirmed it has taken delivery of a fifth ATR, just as the island was battered with bad weather.
Two Channel Islanders among those allegedly poisoned with methanol in Laos
Two sisters from the Channel Islands were among a group of tourists suspected to have consumed alcohol tainted with methanol in Laos.
Disruptive weather conditions cause fallen trees and floods in the Channel Islands
Strong winds and heavy rain is causing major disruption in the Channel Islands.
