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.
Man (33) arrested following a bomb scare in a Guernsey nightclub
Police enquiries continue following an incident at Folies nightclub.
Guernsey FC's play-off final to be held at Victoria Park
Guernsey FC will officially be able to compete for promotion on home soil, after league's U-turn.
Guernsey celebrates 81 years of Liberation
The main focus is on St Peter Port with some 20,000 people expected to come and go during the day.
Survey launches on future use of Guernsey's territorial waters
People in Guernsey are being asked to share their views on how the island’s surrounding waters should be used.
WW2 bombs to be left undisturbed near Guernsey housing estate
The UK Ministry of Defence say the fuses on 2,000lb weapons are not armed and the bombs are 'highly unlikely' to self detonate.
Guernsey FC's play-off final moved to the UK
The club says it will lose home advantage and it does not accept the league's decision.
Guernsey deputy loses committee support
Policy and Resources says it will not nominate deputy Gavin St Pier when he resigns from the committee to seek re-election.
Iconic football trophies to be displayed in Guernsey
Islanders will be able to see pieces of football history in person later this month.
