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.
Guernsey's ready mix concrete prices high but fair
Ronez enjoys a monopoly but the competition regular says its prices reflect costs and are not exploitative.
Guernsey's heatwave ends with a thunderstorm after hottest day ever
Thunder rolled in from France after Guernsey sizzled in its hottest ever recorded temperature.
Inter-island women's football tournament kicks off in Guernsey
Who will be victorious in the 2026 Cherry Godfrey Cup?
LISTEN: Lindsay de Saumarez tells Island FM what tax reforms mean for you
Senior politician Lindsay de Sausmarez explains the effect on our pockets of GST and the reforms designed to soften its blow.
Guernsey hosts Commonwealth Games King's Baton Relay
The King’s Baton Relay arrives in Guernsey today ahead of next month’s Commonwealth Games.
Guernsey milk yields fall because of the extreme heat
The prized Guernsey cows are not eating as usual in the June heatwave, meaning they're producing less milk.
Guernsey actors land key roles in upcoming Occupation film
The first cast members for Under the Watchful Gaze have been announced.
Guernsey pet owners urged to take extra precautions during extreme heat
With record-breaking temperatures in Guernsey, the GSPCA has issued advice to prevent unnecessary animal suffering.
