Specialist officers are examining a property in Mill Street following an 'unexplained death'.
Officers carried out a welfare check this afternoon (10 December) at a flat on Mill Street.
They found a deceased man inside, believed to be 53 years old.
A crime scene cordon is in place, and detectives want to speak to anyone with information.
The Criminal Investigation Department can be contacted on 01481 222 222.
Alderney Airport could close for "an extended period" for runway modifications
Guernsey politicians are set to debate a £24M to upgrade to Alderney’s airport runway, which could require a lengthy closure next year.
Guernsey investor buys large Jersey hospitality group
JPRestaurants, which runs Banjo, Oyster Box and Crab Shack, is changing hands.
Fallen trees in Guernsey could be in the 'low thousands' following Storm Goretti
Guernsey Trees For Life plan to begin a public fund to help buy and plant replacement native trees.
Schools in Guernsey reopen but minor roads remain blocked following Storm Goretti
Guernsey's States say access to the Castel school and Les Beaucamps is affected by road closures caused by fallen trees.
Guernsey's emergency services assess the impact of Storm Goretti
The major incident saw multi-agency responses to nearly 150 emergency calls.
Aurigny gets monopoly on Guernsey's lifeline airlinks as Loganair is denied permits
Loganair's licence applications to operate flights from Guernsey to Jersey and Guernsey to Southampton have been denied by the island's Transport Licensing Authority.
Storm causes gable end to collapse on Guernsey property
An elderly couple had the gable end of their home ripped apart by Storm Goretti but were thankfully uninjured.
Major clean up begins after Storm Goretti
The Bailiwick has been battered by Storm Goretti, with trees brought down, property damaged and 50 people evacuated from flats in St Peter Port.
