Connecticut State Police to release final Sandy Hook report

Robert F. Bukaty / AP

Connecticut State Police will release their official report Friday on the chilling texts, photos and 911 calls investigated by authorities in the Newtown school shooting.

The long-awaited document - described as thousands of pages long - is expected to offer the same conclusions already made in a local prosecutor's report in November. Still, its release marks the end of the state police's exhaustive probe of a tragedy that stunned the country and once again put school gun violence in the forefront of national debate.

Gunman Adam Lanza fatally shot his mother in their Newtown home before driving to Sandy Hook Elementary School and using a semiautomatic rifle to massacre 20 students and six educators on Dec. 14, 2012, officials said. The 20-year-old committed suicide with a Glock 20 pistol as cops closed in on him.

What remains a mystery is his motive for the carnage. The lead prosecutor could determine only that Lanza had been bullied as a child and was obsessed with mass murders.

The troubled killer suffered from 'significant mental health issues,' according to a summary of the state police report, which will be released in full at 3 p.m. ET Friday.The report says he was diagnosed in 2005 with a mild form of autism, known as Asperger's, which is not associated with violent behavior. He also exhibited strange behavior, including having his food arranged onto the plate a certain way and changing his clothes often in a day, news3blog.blogspot.com reported.

State police have been criticized for the delay in the report's release.

But families of those who were killed are also angry that they aren't being given copies of the report before the public, the Danbury-News-Times reported. Relatives said they were told they could review the report beforehand.

Watch US News crime videos on NBCNews.com