Jeremy Richman's body was opened in his office building in Connecticut, Newtown police said.
His death is the third suicide last week linked to school massacres.
49-year-old Richman is the father of Avielle Richman, who is among the 20 children who died in the shooting at Sandy Hook's primary school.
Police said they would "not reveal the method or other details of death," except it does not seem to be suspicious.
Parkland mourns 2 suicides Year after the massacre
In Florida, the mourners grieve for the death of Sidney Aiello, who graduated from high school, Maryrey Stoneham Douglas in 2018, who died of suicide last week. She survived the attack on Valentine's Day 2018, killing 17 people at the Parkland school. ” data-src-mini=”//cdn.cnn.com/cnnnext/dam/assets/181126191024-01-marjory-stoneman-douglas-hs-112618-small-169.jpg” data-src-xsmall=”//cdn.cnn.com/cnnnext/dam/assets/181126191024-01-marjory-stoneman-douglas-hs-112618-medium-plus-169.jpg” data-src-small=”http://cdn.cnn.com/cnnnext/dam/assets/181126191024-01-marjory-stoneman-douglas-hs-112618-large-169.jpg” data-src-medium=”//cdn.cnn.com/cnnnext/dam/assets/181126191024-01-marjory-stoneman-douglas-hs-112618-exlarge-169.jpg” data-src-large=”//cdn.cnn.com/cnnnext/dam/assets/181126191024-01-marjory-stoneman-douglas-hs-112618-super-169.jpg” data-src-full16x9=”//cdn.cnn.com/cnnnext/dam/assets/181126191024-01-marjory-stoneman-douglas-hs-112618-full-169.jpg” data-src-mini1x1=”//cdn.cnn.com/cnnnext/dam/assets/181126191024-01-marjory-stoneman-douglas-hs-112618-small-11.jpg” data-demand-load=”not-loaded” data-eq-pts=”mini: 0, xsmall: 221, small: 308, medium: 461, large: 781″ src=”data:image/gif;base64,R0lGODlhEAAJAJEAAAAAAP///////wAAACH5BAEAAAIALAAAAAAQAAkAAAIKlI+py+0Po5yUFQA7″/>
Aiello, a University of Florida student diagnosed with post-traumatic a stress disorder, her mother told CNN's WFOR.
Then on Saturday, a second student from Marrie Stoneman Douglas died in what the police described as "obvious suicide."
The student is not publicly identified. It is unclear under what circumstances the student has died or whether the apparent suicide is related to last year's slaughter.
Father was a Force to Change
After Sandy Hook's massacre, Richman tried to make sure that shooting like the one who murdered his daughter would not be repeated again.
Neurologist co-founded The Avielle Foundation draws attention to the problems of mental health through research and community engagement.
"The mission of the Avielle Foundation is two-sided, we have research, and we fund neurological research aimed at understanding the chemistry, structure and patterns of the brain that lead to violence and compassion," the foundation's website .
The other side is "focused on community education and engagement". If you or someone you know is at risk of suicide, here's how you can get help : In the US, call National Suicide Prevention Plan 1-800-273 -8255. The International Association for the Prevention of Suicides and Befrienders Worldwide can also provide contact information for crisis centers around the world.