"There was nothing earth-shattering in any of these images," Witt said.
Police took another look at the Cobain suicide to be ready to answer questions in connection with next month's anniversary, she said.
"There's still a lot of interest in this case," Witt said. "The detective went into the case files to refresh himself. The outcome of the case has not changed."
Cobain's body was discovered in Seattle on April 8, 1994. An investigation determined that days earlier Cobain 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 tranquilizers.
Cobain, who was 27 when he died, sold millions of albums with Nirvana and helped popularize the Pacific Northwest's heavy, muddy "grunge" rock, along with bands like Pearl Jam, Soundgarden, Alice in Chains and Mudhoney.
After his death thousands of young people converged on Seattle Center, near the Space Needle, for a public memorial.
Cobain grew up in the logging town of Aberdeen, Wash., about two hours west of Seattle. A riverfront park there is dedicated to his memory.