The state of Connecticut has made public the documentation of its massive investigation into the 2012 shooting at Sandy Hook Elementary School.
The state's Department of Emergency Services and Public Protection released photos, videos, 911 calls and thousands of pages of documents on its website Friday.
See also: Sandy Hook Victims' Families Launch Heartfelt Online Memorial
A two-page letter from Connecticut State Police Commissioner Reuben Bradford accompanied the documents.
"The investigation of this incident is unparalleled in the 110-year history of the Connecticut State Police," Bradford wrote. "Tens of thousands of hours were spent by investigators from all over the country tracking down leads, processing evidence and doing everything within their collective ability to provide answers for the questions that remained in the wake of the terror of that morning."
In a summary of the investigation released in November, state prosecutors say 20-year-old Adam Lanza gunned down 20 first graders and six adult staff members using a semi-automatic rifle during a 10-minute period, beginning at 9:30 a.m. ET on Dec. 14, 2012.
The state attorney's summary said Lanza "had a familiarity with and access to firearms and ammunition and an obsession with mass murders." It also noted that he suffered from a high levels of anxiety, Obsessive Compulsive Disorder and "Asperger’s characteristics."
Though the documentation released Friday is comprehensive, a significant portion of it has been redacted. A redaction index, which codifies each blacked-out page, also accompanied the document release. Bradford, in his letter, discussed the redactions further, saying it was difficult to achieve a balance between government transparency and individual privacy.
"I hope that the release of this report, though painful, will allow those who have been affected by it to continue in their personal process of healing," Bradford wrote, "and will provide helpful information that can be put to use to prevent such tragedies in the future."
Bradford recently announced his retirement, effective Feb. 1. Connecticut Gov. Dannel Malloy appointed Bradford to the position in Dec. 2010. Bradford was the first African American to serve as Connecticut's top cop.
For more on the Sandy Hook investigation, the full stockpile of documents in the investigation is available for download here.
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