Shooting massacre ... Adam Lanza. Credit:AP Authorities had hoped its data would shed light on Lanza's deadly killing spree. Detectives have so far been unable to provide any definitive link between the young man and the school he attacked. ''It looked like he took steps to damage it - he smashed it,'' an official connected to the investigation told the New York Times. Federal investigators have interviewed at length both Lanza's father Peter, a tax specialist, and his elder brother Ryan, 24, in an effort to determine the catalyst behind the attack. But despite hours of questioning it is understood the pair were unable to explain why Lanza acted so violently. ''In all that time, they got no real information that could help figure this out,'' said an official, who wished to remain anonymous. Meanwhile, Lieutenant Paul Vance, a spokesman for state police, said investigators were continuing to ''examine everything and anything'' relevant to the shooting, including mobile phones and computer game consoles.

Barack Obama ... 'We have a deep obligation.' Credit:AP Officials said they were also aware that Lanza had been a keen computer gamer, and enjoyed some of the particularly violent varieties of war games. FBI investigator Robert Paquette said: ''Many of these games are very violent. I can't help but believe these can affect the mind of someone unbalanced.'' Christmas stockings with the names of shooting victims hang from railing near a makeshift memorial in Sandy Hook. Credit:AP No letters or notes from Lanza have been found offering a motive.

Police are also likely to concentrate their efforts on statements provided by vice-principal Natalie Hammond, 40, who is recovering in hospital after being injured in the shooting. The fact that this problem is complex can no longer be an excuse for doing nothing. The teacher, along with a second survivor who is understood to be an employee at the school, will be vital in helping piece together an explanation for the tragedy. A spokeswoman for the Office of the Chief Medical Examiner in Farmington, Connecticut, confirmed that no family member had yet come forward to claim the bodies of Lanza or his mother. President Obama set a January deadline for new gun control recommendations, tasking asked Vice President Joe Biden with leading the effort and vowed to push for implementation of the policy proposals without delay.

"This time, the words need to lead to action," he said. "We may never know all the reasons why this tragedy happened. We do know that every day since, more Americans have died of gun violence. "If there is even one thing that we can do to prevent any of these events, we have a deep obligation, all of us, to try...The fact that this problem is complex can no longer be an excuse for doing nothing.'' The President also called on Congress on Wednesday to reinstate an assault weapons ban that expired in 2004 and to pass legislation that would close the gun show "loophole," which allows people to purchase firearms from private dealers without a background check. Obama also said he wanted Congress to pursue the possibility of limiting high-capacity ammunition clips. ■On the first school day after the Newtown shooting, an 11-year-old boy brought a gun to his Utah elementary school, apparently fearful a similar massacre could happen there, officials said.

Loading Granite School District spokesman Ben Horsley said the sixth-grader at West Kearns Elementary School allegedly waved a .22-calibre handgun at three students on Monday during a lunch break. A teacher was told about the gun, which was found in the student's backpack and unloaded. ''He wanted to defend himself and his friends, based on what he's seen on the news,'' Mr Horsley said the boy told police. TELEGRAPH, LOS ANGELES TIMES and AGENCIES