New court documents show the pupil confessed to the attack and outline how he took his mother's gun.
The six-year-old student who shot his teacher in the US earlier this year, boasted about the incident saying "I shot [her] dead", unsealed court documents show.
While being restrained after the shooting at a Virginia school, the boy is said to have admitted "I did it", adding "I got my mom's gun last night".
His teacher, Abigail "Abby" Zwerner - who survived - filed a $40m (£31.4m) lawsuit earlier this year.
The boy has not been charged.
The boy's mother, however, Deja Taylor, has been charged with felony child neglect and misdemeanour recklessly leaving a loaded firearm as to endanger a child.
In Ms Zwerner's lawsuit, filed in April, she accuses school officials of gross negligence for ignoring warning signs and argues the defendants knew the child "had a history of random violence
The documents also mention another incident with the same student while he was in kindergarten. A retired teacher told police he started "choking her to the point she could not breathe".
Y'all are acting outraged while this boy could've stopped the Sandy Hook-shooting. It's only due to unlucky circumstances that he happened to shoot his teacher instead. Wrong place, wrong time. Poor boy.