State officials have released a long-awaited report on last December’s Newtown Elementary School shooting, which concludes that the 20-year-old Adam Lanza acted alone when he fatally shot his mother at their home in Newtown and then went to the elementary school where he fatally shot 20 first-grade pupils and six adults and wounded two other adults.

“The purpose of the investigation was to determine what crimes had been committed and whether anyone will be prosecuted as a result of those crimes. Based on a painstaking investigation it is determined that there will be no arrests or prosecutions. The Connecticut State Police are to be commended for their tireless work on this investigation and their consideration of the families and victims involved,” said the report’s author, Danbury State’s Attorney Stephen Sedensky III.

But Sedensky said despite the depth of the investigation, there is one question that might never be answered.

“The obvious question that remains is: ‘Why did the shooter murder twenty-seven people, including twenty children?’” Sedensky’s report stated. “Unfortunately, that question may never be answered conclusively, despite the collection of extensive background information on the shooter through a multitude of interviews and other sources. The evidence clearly shows that the shooter planned his actions, including the taking of his own life, but there is no clear indication why he did so, or why he targeted Sandy Hook Elementary School.

The report, however, did reveal evidence of Lanza’s mental health problems. “What we do know is that the shooter had significant mental health issues that, while not affecting the criminality of the shooter’s mental state for the crimes or his criminal responsibility for them, did affect his ability to live a normal life and interact with others,” Sedensky said.

Investigators recovered violent video games, violent videos of shooting events and photos of Lanza holding a gun to his head, but they acknowledged that a sizeable amount of information would not be revealed because Lanza had destroyed his computer.

Based on interviews with people who knew Lanza, the report said, “those who knew the shooter describe him in contradictory ways. He was undoubtedly afflicted with mental health problems; yet despite a facination with mass shootings and firearms, he displayed no aggressive or threating tendencies.”

The report indicates that nearly six minutes passed between the arrival of the first Newtown police officer and the time local officers entered the school. A timeline released with the report says the first officer arrived behind the school at 9:39 a.m. after the shooting was reported. Two other Newtown officers then arrived at the school, and gunshots were heard in the background.

The last gunshot officers heard, which is believed to be the suicide shot by Adam Lanza, was heard at three seconds past 9:40.

The report says Newtown officers entered the school at 47 seconds past 9:44.

There had been some criticism from public officials and open records advocates about the length of time it was taking Sedensky to release the results of the state investigation. In fact, the 44 pages released Monday represent only a fraction of the information gathered by investigators. A full report is scheduled to be released early next year.

“A release of a summary report before the release of the full report is highly unusual,” said John Thomas, a professor at Quinnipiac University Schools of Law & Medicine, who studies issues surrounding mental health and gun laws.

Dan Klau, a Hartford attorney who specializes in First Amendment law, agreed that the decision to release a summary report before the full evidence file is a reversal of standard practice.

“What I found troubling about the approach of the state’s attorney is that from my perspective, he seems to have forgotten his job is to represent the state of Connecticut,” said Klau, who practices at McElroy, Deutsch, Mulvaney & Carpenter. “His conduct in many instances has seemed more akin to an attorney in private practice representing Sandy Hook families. What I found troubling about the approach of the state’s attorney is that from my perspective, he seems to have forgotten his job is to represent the state of Connecticut.”

But Morgan Rueckert, a Shipman & Goodwin attorney in Harford who is representing 22 of the Sandy Hook victims’ families, said it is important for the government to keep the victims in mind when releasing information.

“I think it’s appropriate under these circumstances to take a harder look now at what should be released and in what manner,” Rueckert said. “For those clamoring for the release of detailed information of the mechanism of how a heavily armed person smashed their way into an Elementary School and murdered 26 children and teachers — I must respond that there is no mystery there, schools are not fortresses, and why do you need to know who was shot when and how, what purpose is served other that satisfaction of morbid curiosity? The important question rather is about Adam Lanza, and how he had access to guns, and ammunition and how he was allowed to plan this and how his so very serious problems were not properly addressed.”

Gov. Dannel Malloy weighed in on the report shortly after its release.

“My thoughts today are with the people who lost a loved one at Sandy Hook Elementary School, as they have been nearly every day since the tragedy. The release of this report will no doubt be difficult on them. But if there is one thing that I believe we must do, it’s that we must honor the lives that were lost by taking steps to protect ourselves from another horror like this. I hope that the information in this summary and in the supporting documents that will be released by the State Police takes us closer to that goal.”