Another Suicide} Jeremy Richman Father of Sandy Hook Killing of His Daughter Killed Himself

 Jeremy Richman stands the backyard of his home in 2013. His daughter Avielle was killed in the 2012 Sandy Hook school shooting.

By Holly Yan, CNN

A father dedicated to helping prevent mass shootings after his daughter was killed in the Sandy Hook massacre has died of an apparent suicide. 

The body of Jeremy Richman was found in his Connecticut office building Monday morning, Newtown police said. 

His death is the third suicide in the past week related to school massacres. 

Richman, 49, was the father of 6-year-old Avielle Richman, who was among 20 children and six adults killed in the 2012 Sandy Hook Elementary School shooting.

Avielle Richman, 6, was killed in the Sandy Hook shooting.

Police said they "will not disclose the method or any other details" of Richman's death, other than it does not appear to be suspicious.

Parkland grieves 2 suicides a year after massacre

In Florida, mourners are grieving the death of Sydney Aiello, a 2018 graduate of Marjory Stoneman Douglas High School who died by suicide last week. She survived the attack on Valentine's Day 2018 that killed 17 people at the school in Parkland. 

After 2 student suicides, Parkland dad tells parents everywhere to be alert

Aiello, a Florida Atlantic University student, suffered from survivor's guilt and had been diagnosed with post-traumatic stress disorder, her mom told CNN affiliate WFOR. 

Then on Saturday, a second Marjory Stoneman Douglas student died in what police describe as "an apparent suicide." 

The student has not been publicly identified. It's not clear under what circumstances the student died, or whether the apparent suicide was related to last year's massacre. 

Father was a force for change

After the Sandy Hook massacre, Richman tried to help make sure shootings like the one that killed his daughter wouldn't happen again. 

5 years after Sandy Hook, the victims are not forgotten

The neuroscientist co-founded the The Avielle Foundation, which calls attention to mental health issues through research and community engagement. 

"The Avielle Foundation's mission is two-sided. On the one side we have research. We are funding neuroscience research aimed at understanding the brain's chemistry, structure, and circuits that lead to violence and compassion," the foundation's websitestates. 

The other side is "focused on community education and engagement." 

If you or someone you know might be at risk of suicide, here's how to get help: In the US, call the National Suicide Prevention Lifeline at 1-800-273-8255. The International Association for Suicide Prevention and Befrienders Worldwide also can provide contact information for crisis centers around the world.

CNN's Julia Jones and Dakin Andone contributed to this report.