Police in Seattle have released photographs of the shotgun Nirvana frontman Kurt Cobain used to kill himself more than two decades ago.

Cold case detective Mike Ciesynski is shown holding Cobain’s gun at different angles in five photos posted to the police department’s website.

The pictures were taken in June 2015, put on the city of Seattle’s computer system on 3 March and since then have been added to the investigative file, according to police.

It is unclear why they took the photos last year or why they are now releasing them to the public.

A message left with Seattle police was not immediately returned.

Cobain’s body was found in Seattle on 8 April 1994. An investigation determined that days earlier the singer had gone into the greenhouse of his large home and taken a massive dose of heroin. He then shot himself with a 20-gauge shotgun. His death was ruled a suicide.

On the 20th anniversary of Cobain’s death in 2014, Ciesynski reviewed the case files and said he found no new information to change the police conclusion that he took his own life. He did find four rolls of undeveloped film from the suicide scene.

After releasing two of the images in 2014, police released 34 additional photographs taken at the scene due to numerous public disclosure requests for the images.

Cobain, who was 27 when he died, helped popularise the Pacific north-west’s grunge rock music, along with bands like Pearl Jam, Soundgarden, Alice in Chains and Mudhoney.