Many experts say neither Asperger's syndrome nor autism can be blamed for the rampage.
"There is absolutely no evidence or any reliable research that suggests a linkage between autism and planned violence," the Autism Society said in a statement. "To imply or suggest that some linkage exists is wrong and is harmful to more than 1.5 million law-abiding, nonviolent and wonderful individuals who live with autism each day."
Dr. Max Wiznitzer, a pediatric neurologist and autism expert at Rainbow Babies and Children's Hospital in Cleveland, also said the gunman's actions can't be linked to autism spectrum disorders.
"Aggression and violence in the ASD population is reactive, not preplanned and deliberate," he said.
Two very premature funerals
While adults and children try to move on, two more 6-year-olds from Sandy Hook were being laid to rest Tuesday.
Jessica Rekos was obsessed with horses -- horse books, horse movies, drawing horses and writing stories about them. She was eagerly anticipating a pair of cowgirl boots for Christmas.
As her relatives grieve, they are also "trying to help her brother Travis understand why he can't play with his best friend," her family said.
James Mattioli liked to remind everyone that he was 6 and three-quarters. "He would often sing at the top of his lungs, and once asked, 'How old do I have to be to sing on a stage?'" his family wrote in an obituary.
In an online posting about his funeral, the Mattioli family called James "our beloved prince."
Also on Tuesday, the family of 6-year-old Charlotte Bacon planned to hold calling hours, or visitation.
Charlotte was a bundle of energy under her distinctive red curls. She also loved school and dresses, her grandmother told CNN affiliate WCCO in Minnesota.
Calling hours are also being held for 7-year-old Daniel Barden on Tuesday.
His "fearless" pursuit of happiness and life earned him two missing front teeth and ripped jeans, his family says. His mother described him as "just so good."
There are also calling hours Tuesday for Victoria "Vicki" Soto, a 27-year-old teacher who moved her students away from a classroom door when she heard gunfire. She was a hero, cousin James Wiltsie said.
The funerals will carry on for days. Some residents in this emotionally drained community plan to attend many this week.