GUY RAZ, HOST:
It's WEEKENDS on ALL THINGS CONSIDERED, from NPR News. I'm Guy Raz. Tomorrow in Fairfield, Connecticut, 6-year-old Noah Pozner will be laid to rest. Relatives say his twin sister, Arielle, was his best friend. Noah and Arielle were in different first-grade classes. She survived the rampage at Sandy Hook Elementary.
Over the coming days, we will learn more about the 26 children and adults who were killed there; heartbreaking stories that for many of us, may be too difficult to bear. This evening, President Obama arrived in Newtown, to be with the families of the victims. Meanwhile, there is an investigation to carry out. Police say they have weeks of work ahead of them. Authorities still need to interview dozens of witnesses, including traumatized children. NPR's justice correspondent Carrie Johnson is here with us, to talk about the investigation. Carrie, what new details are emerging about the gunman?
CARRIE JOHNSON, BYLINE: Guy, we're learning more about the cause of death for the gunman, Adam Lanza; and his mother, Nancy Lanza. The medical examiner reports that Adam Lanza died from a self-inflicted gunshot wound to the head - inside the school, with a handgun he carried. And his mother, Nancy Lanza, was the victim of a homicide. She suffered multiple gunshots wounds to the head. We don't know what weapon was used to attack her inside that house in Newtown, Connecticut.
RAZ: What about the weapons in the case, though - have authorities been able to trace them?
JOHNSON: Yes. The Bureau of Alcohol, Tobacco and Firearms has been able to trace all of these weapons. [POST-BROADCAST CLARIFICATION: The official name of the U.S. Department of Justice agency known as ATF is the Bureau of Alcohol, Tobacco, Firearms and Explosives.] They all appear to have been legally purchased in the name of Nancy Lanza, the gunman's mother. And at a recent briefing, Lt. Paul Vance, of the Connecticut State Police, has said the gunman, Adam Lanza, had in his vehicle - in the school parking lot - another weapon that was apparently not used in the attack. He also confirmed, for the first time, that that .223-caliber Bushmaster rifle - used to shoot all of the children, and the adults, inside the school - was equipped with a high-capacity magazine; and that the two handguns Adam Lanza carried with him inside the school, also were equipped with multiple magazines. Lt. Vance said hundreds of bullets were expended in the course of this attack, Guy.
RAZ: What questions are investigators still trying to answer?
JOHNSON: Lots of questions. Adam Lanza is dead; he does not appear to have acted with any co-conspirators. That said, authorities want to know whether he was on medication, undergoing any kind of psychiatric treatment. Why did he target the school, Guy? He's left no written note, federal law enforcement sources tell me. So they're looking, and doing forensic examination now, of material they got from inside the house in Newtown. They've executed numerous search warrants there. And Lt. Vance says every stitch of that evidence needs to be analyzed. Because we know Adam Lanza was characterized - by a source of mine in the federal government - as a recluse, he didn't have many friends that they can interview now - in law enforcement. So any computer activity he may have engaged in, could be key to understanding his motive.
RAZ: We talk about closure, at times like these, but - I mean, there will be no trial. I mean, that's it - after the investigation.
JOHNSON: There will be no trial, but authorities offered a bit of a warning today, Guy. Both Lt. Vance, of the state police, and the U.S. attorney - the top federal prosecutor in Connecticut, have warned people not to harass victims, relatives or witnesses at the school. If you do so via email, via telephone or in person, they said you could be prosecuted.
RAZ: And is that happening - those social media harassments?
JOHNSON: Lt. Vance indicated that some people have been harassed, but he didn't characterize that harassment in detail today.
RAZ: That's NPR's justice correspondent Carrie Johnson, updating us on the investigation into that shooting. Carrie, thanks.
JOHNSON: Thank you. Transcript provided by NPR, Copyright NPR.