Prosecutors are set to release a report on the nearly year-long investigation into the massacre at Sandy Hook Elementary at 3 p.m. Monday, and many hope the report will help answer key questions about the mass shooting. Among the questions:
Why did Adam Lanza do it?
Why did 20-year-old Adam Lanza kill his mother and then 20 first-graders and six staffers at the Newtown, Conn. School before taking his own life last Dec. 14? Speculation has centered on the possibility that his mother Nancy might have wanted him to leave the home and attend school.
What was Lanza’s plan?
Did Adam Lanza mean to end the assault with his suicide, or did he intend further carnage? Why did he leave a shotgun outside with his car? It’s known that Lanza kept a spreadsheet on previous mass shootings. A hard drive found in the home was seriously damaged, and data recovery was previously said to be extremely difficult.
What’s in Adam Lanza’s diaries?
Investigators found several diaries and journals kept by Lanza. Will the report disclose what they contained and were the contents helpful to investigators?
Is there more to know about Lanza’s medical history?
Had Lanza been prescribed any psychiatric medication, and had he stopped taking a prescribed medication? As previously reported, a toxicology report on Lanza's body yielded no substances. Was there an unknown diagnosis that might help explain his actions?
Did the video games matter?
According to search warrant affidavits, an unnamed witness told FBI agents following the shooting that Lanza was known for playing the violent video game "Call of Duty." Several video game systems were found in the Lanza home, including one with a partially obliterated serial number. Do investigators believe they played any role in his actions?
Was the police response good enough and fast enough?
Some media sources said police were ordered to wait before entering the Sandy Hook school building last Dec. 14. Police have stated in numerous press conferences and interviews that there was no such order. Officers say they went into the school according to procedure, arriving less than two minutes after the first call went out. Local police arrived first, followed within moments by the state police.
Separately, at a hearing in New Britain, Conn., Monday morning, prosecutor Stephen Sedensky III argued against the release of around 40 minutes of 911 recordings from the day of the shooting. The state Freedom of Information Commission ordered the recordings released in September, but Sedensky has appealed the order. Judge Eliot Prescott said he will listen to the tapes and rule on their release, but will not issue the ruling Monday.
According to sources briefed on the investigation, the summary to be released today by Danbury State’s Attorney’s Office, which has jurisdiction, may not provide clear answers to the outstanding questions about the case. Approximately 40 pages in length, it’s based on a full police report that will surely have much more detail, but still has no scheduled release date. Lt. Paul Vance, a spokesperson for the Connecticut State Police, told NBC News that the full police report used to develop the summary is "several thousand pages" in length, and is being redacted in preparation for its release.
According to the Hartford Courant, today’s release may include new pictures of the school. It will not include any pictures of the victims, because of a state law passed in response to the shooting that blocks the release of such images.
The report will be released via the state’s Division of Criminal Justice website, www.ct.gov/csao.
In advance of the summary report being issued, Sedensky’s office allowed victims' relatives to review the report at briefings. The interim superintendent of schools in Newtown also reached out to parents and sent a letter to ensure they’re prepared.
"We all understand that for the children who were directly affected by this tragedy the release of the report and the upcoming anniversary can carry a very personal meaning," said the letter.
More from NBC News Investigations: