NEW BRITAIN, Conn. — Nelba Marquez-Greene believes the Sandy Hook Elementary School massacre, which killed her 6-year-old daughter, could have been avoided if more had been done years earlier to address the social isolation and mental health problems of the shooter, Adam Lanza.

To help other vulnerable youths, Marquez-Greene, a family therapist, is working with a Connecticut school system on a program to help students connect.

“I want people to remember that Adam, the person who did this, was also once 6 and in a first-grade classroom, and that if we had reached out earlier then maybe this could have changed,” she said.

Marquez-Greene’s Ana Grace Project foundation, named for her slain daughter, is working with four elementary schools in New Britain, a city just west of Hartford, to teach empathy, combat bullying and help socially isolated children.