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 FC receives financial support from local entrepreneurs
Two Guernsey business couples are backing GFC with multi-year financial support.
Guernsey footballer Alex Scott called up to England squad
Bournemouth midfielder Alex Scott has received his first senior call-up for the Three Lions.
Guernsey's skin cancer rates higher than England
The latest Public Health report shows malignant and non malignant melanomas are the most preventable form of cancer.
Guernsey ambulance subscriptions to increase by 1p a day
The St John Ambulance and Rescue Service says islanders should consider joining the Ambulance Subscription Scheme to "prevent that bill shock".
Deputies approve Guernsey's budget, with amendments
Mortgage tax relief stays but deputies shy away from freezing committee spending.
Thousands for Guernsey and Jersey schools to boost active travel
The Better Journeys Project has money for Channel Island schools to promote cycling, walking and scooting.
Personal reasons prompt Guernsey Deputy’s departure from ESC
Guernsey's Education, Sports and Culture Committee will begin looking for a new member after Deputy Jayne Ozanne announced her decision to leave.
New Aurigny aircraft flies into Alderney
The Twin Otter is owned, flown and maintained by Skybus under a new contract with Aurigny.
