The family of Colleen Ritzer has filed a civil lawsuit over her death at the hands of a Danvers High School student, demanding answers from the town, the school system where she was a popular teacher, and two contractors whose alleged mistakes added to her loved ones’ grief.

The suit comes nearly three years after Ritzer, 24, was killed by Philip D. Chism in an attack that began in a school bathroom. Chism was convicted of murder, rape, and robbery.

The suit, filed Tuesday in Essex Superior Court, said family members are not seeking personal financial compensation.

The family is instead trying to gain a better understanding of what happened and are looking for money to “enhance school safety programs and to contribute to the legacy of Colleen Ritzer,’’ the suit states.

Along with the town and the school system, the suit names among the defendants SJ Services, which was hired by the school to do janitorial work.

Another defendant is DiNisco Design Partnership, which provided a security system for Danvers High School.

Town and school officials declined to discuss the suit.

“At this point we cannot comment on the pending litigation,’’ Superintendent Lisa Dana said. “We are, however, committed to continuing Colleen Ritzer’s legacy of kindness and dedication to teaching.’’

Andy Rosen can be reached at andrew.rosen@globe.com. Follow him on Twitter at @andyrosen.