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.
Second man jailed for inter-islands drugs trafficking operation
Timothy Ayres has been jailed for two and a half years after he and a man from Guernsey were arrested for drug offences and financial crimes.
Guernsey's airline explains why it 'soft launched' its latest ATR
Aurigny says it did not want to put its red and white leased ATR into full service straight away to avoid any potential for disruption to passengers.
Islands Energy boss Jo Cox steps down
The CEO of Islands Energy, the Channel Islands' gas supplier, has resigned after almost four years in charge.
