Gunman Adam Lanza wore yellow ear plugs that muffled the screams of his victims at Sandy Hook Elementary School and he shot himself in the mouth after committing one of America's worst school massacres.
Disturbing details about last year's mass shooting in the small Connecticut town of Newtown were revealed on Friday when US police released thousands of pages of documents, photographs and recordings from their investigation.
The troubled 20-year-old shot dead 20 first grade children and six adults using a rifle taken from his suburban mother's legally acquired home defence arsenal.
Lanza was dressed almost entirely in black and his clothes - a shirt, T-shirt, cargo pants, boxer shorts, socks, sneakers, belt and fingerless gloves - were found spattered with blood and gunpowder after the murders.
"Two law enforcement officers arrived during the shooting, at which time the suspect ducked into a classroom and shot himself," says an FBI incident report contained in the file. Lanza shot himself in the mouth, shattering his brain and skull, according to the attached forensics report.
The documents are the latest pieces of chilling evidence that expose some of the terror that Lanza's victims endured on December 14, 2012.
More than a dozen bodies, mostly children, were discovered packed "like sardines" in a bathroom where they had hidden. And the horrors encountered inside the school were so great that when police sent in paramedics, they tried to select ones capable of handling what they were about to witness. "This will be the worst day of your life," police sergeant William Cario warned one.
Last month, prosecutors issued a summary of the investigation that portrayed Lanza as obsessed with mass murders and afflicted with mental problems. But the summary said his motive for the massacre was a mystery and might never be known.
According to at least one witness interviewed by the FBI, Lanza and his mother Nancy owned at least four firearms, which were kept in a gun safe in the school shooter's bedroom closet.
Witness testimony, which has been redacted to remove names, also revealed little known details about Lanza, who suffered from Asperger's Syndrome.
He was a vegan, interested in Japanese techno music and had been taking Chinese lessons. He also knew how to build a computer from scratch. The report also included many photographs including one of a young child holding what appears to be a gun, with ammunition in his lap.
Lanza's mother once took him out of school because he was sensitive to sound and light and photographs showed windows taped over with bin liners.
Lanza carried out the murders the morning after his mother returned from a few days away, which she told one friend had been an "experiment" to allow him to stay home alone.
Additional reporting by The New York Times, Agence France-Presse