State Police Commissioner Rueben F. Bradford called the multi-pronged investigation that followed the Dec. 14, 2012, massacre at Sandy Hook Elementary School unparalleled in the 110-year history of the state police.

While local, state and federal agencies all were involved in trying to unravel the course of events that day, the brunt of the work fell to state police detectives, as detailed in the reams of paperwork associated with the investigation released on Friday.

While the primary investigation centered on the school and killer Adam Lanza, members of the state police Eastern District Major Crime Squad, led by Detective David Lamoureux, traveled to Lanza's home to investigate the death of Lanza's mother, Nancy Lanza. The group typically handles all major investigations in a 42-town area covering Tolland, Windham, Middlesex and New London counties.

Their conclusion is a blunt one. Between 8 and 9 a.m. on Dec. 14, 2012, Adam Lanza entered his mother's bedroom and shot her four times in the head with a .22 caliber rifle as she lay in bed. He left the gun on the floor near his mother, locked the house and drove her 2010 black Honda Accord to Sandy Hook Elementary School, where he shot and killed 20 students and six educators before shooting himself.

The summary of the investigation belies the numerous hours spent tracking Nancy Lanza's movements, purchases and interactions in the days before the crime. Police processed evidence, conducted numerous interviews and documented the crime scene - all painstakingly documented in the hundreds of pages of partially redacted paperwork released Friday.

State police detectives were not the first into the Lanza home at 36 Yogananda St. in Newtown on the day of the shooting. Records show a state police tactical unit had forced their way in and found Nancy Lanza's body shortly after the school shooting.

Detectives began their search at about 5:30 p.m. after a search warrant was applied for and granted. The search was documented by digital video, photos and a sketched map of the entire house, some of which was included in the documents released Friday.

The detectives worked with members of the FBI's behavioral analysis unit and agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives, who obtained information on the weapons found there.

Among the numerous guns, boxes of ammunitions and paraphernalia associated with target shooting were signs that Nancy Lanza was seeking to better understand her son. Books on a living room shelf included "Look Me in the Eye - My Life with Asperger's," and "Born on a Blue Day - Inside the Extraordinary Mind of an Autistic Savant."

In Adam Lanza's bedroom, police found two windows with shades drawn and edges of the shades affixed to the wall with tape. He had apparently smashed the hard drive of his computer with a 5-pound dumbbell. They found more ammunition, newspaper articles about mass shootings and a .303 caliber rifle inside an open safe in his closet.

Detectives reviewed Nancy Lanza's day planner and learned she had stayed at the Omni Mount Washington Resort between Dec. 11 and Dec. 13. According to an unidentified old friend Nancy Lanza met with while in New Hampshire, "the trip was an experiment to allow Adam to stay at home alone for a few days," according to the police records.

Detectives Jeffrey R. Payette and David Lamoureux traveled to New Hampshire, where they found out where Nancy Lanza had dined, what stores she had visited - even the fact that she had had a muffin delivered by room service at the hotel and bought five bottles of wine on her ride home.

Detectives also learned from an unidentified acquaintance that Nancy Lanza had thought about selling her Newtown home and moving to Washington state or North Carolina, according to the police documents. Adam Lanza had expressed interest in a school in Washington, and Nancy Lanza had told the acquaintance she had a friend in North Carolina who agreed to mentor him.

The sale of the house was postponed, police said, because Nancy Lanza knew she would not be able to show the house with her son there.

Instead, she had apparently developed a plan to purchase a recreational vehicle. During a trip with her son, "she could have Adam out of the house, they could effectuate their move and meanwhile sell her house," according to police records.

g.smith@theday.com