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.
New Commanding Officer of "Guernsey's Warship" visits
HMS Daring could return to Bailiwick waters next year.
New Alderney runway at design stage
The project is not costed yet, but repairs to Alderney runway so far this year have reached £460,000.
States promise action on buried bombs in a Guernsey field
Home Affairs counters claims by munitions expert Ben Remfrey and says the buried ordnance will be dealt with proportionately.
Guernsey man (38) jailed for child sex offences and drug supply
A public tip-off and an 'extensive investigation' have led to the eight-year imprisonment of Steven Beausire for sexual offences against a child and the supply of drugs.
Government 'holds hands up' after warning its own emails were phishing scams
The States of Guernsey has apologised after an email gaffe in which it warned residents that its own messages should be discarded as spam.
Spend on patching Alderney's runway at £460,000 so far this year
The latest repairs to Alderney's runway have taken place overnight to keep the airport operational.
Foundations being laid for 'Learning Village' in Guernsey
After a decade of fundraising, the foundations are being laid for an education centre for students with learning difficulties.
Guernsey mum reunited with rings after rubbish rescue
Thanks to some determined staff at the island’s recycling centre, a Guernsey woman has been reunited with her lost wedding and engagement rings.
