Irving Pinsky told The Hartford Courant he would reserve the right to refile his request to sue for $100 million on behalf of a 6-year-old survivor of the Dec. 14 massacre that left 20 first graders and six staff members at Sandy Hook Elementary School dead.
The state has sovereign immunity against most lawsuits unless permission to sue is granted.
Pinsky would not elaborate on the nature of the evidence but said he had yet to verify it.
Attorney General George Jepsen said Monday Pinsky has no basis to sue the state.
Jepsen said his office was unaware of any "facts or legal theory" indicating the state would be liable for what happened.
"Our hearts go out to this family, and to all the children and families affected by the Newtown shootings," Jepsen said. "They deserve a thoughtful and deliberate examination of the causes of this tragedy and of the appropriate public policy responses."
Before heading to the school, Adam Lanza shot and killed his mother at the home they shared. After killing the students and adults at the school, he killed himself.
Pinsky claimed the state education officials didn't take steps to protect children from foreseeable harm.
Also Monday, the Connecticut Trial Lawyers Association's executive board emailed association members about Pinsky's claim, the Courant said.
"CTLA joins with all other citizens in [Connecticut] in mourning the tragic loss of life in Newtown," the email read. "We believe that the timing and circumstances of this action are ill-advised. We will continue to extend our heartfelt sympathies to the victims of the Newtown tragedy, and we remain committed to joining the efforts of countless individuals in Connecticut and around the country to find ways to assist the victims and families affected by this tragedy."
Pinsky told the Courant he agreed with the association's statement overall, but disagreed with the part concerning his case.
"For my case, what I'm doing is appropriate," he said, adding that the girl's family contacted him.
Wisconsin business offering 'therapeutic cuddling' forced to close
Puzzle-maker slips 'Murdoch Is Evil' into Rupert Murdoch's Sunday Telegraph