Police spokeswoman Renee Witt said that a detective who recently reviewed the Cobain case files found several rolls of undeveloped film that were taken at the suicide scene.
One image shows a box containing a spoon and what look like needles on the floor next to half a cigarette and sunglasses.
The other showed the paraphernalia box closed, next to cash, a cigarette pack and a wallet that appears to show Cobain's identification.
Police took another look at the Cobain suicide in preparation for answering questions in connection with next month's anniversary, Ms Witt said.
Cobain's body was discovered in Seattle on April 8, 1994. An investigation determined that days earlier he 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.
Earlier that year, Cobain had tried to kill himself in Rome by taking an overdose of tranquillisers.
Cobain, who was 27 when he died, sold millions of albums with Nirvana and helped popularize the Pacific Northwest's "grunge" rock.
Though his death was ruled a suicide some refused to believe that, leading to conspiracy theories that Cobain had been killed.
In a statement from the Seattle Police Department, the detective who re-examined the case dismissed that speculation.
"Sometimes people believe what they read - some of the disinformation from some of the books, that this was a conspiracy. That's completely inaccurate," said Detective Mike Ciesynski, who found the undeveloped photos.