HARTFORD, Conn. (AP) — The parents of one of the 20 children killed in the Sandy Hook Elementary School shooting are asking Facebook founder Mark Zuckerberg to remove hateful and harassing comments posted by conspiracy theorists who say the shooting never happened.

Leonard Pozner and Veronique De La Rosa wrote Zuckerberg a letter published on Wednesday in The Guardian . Their 6-year-old son, Noah, died in the December 2012 Newtown shooting massacre, which also claimed the lives of six educators.

Pozner and De La Rosa say they and other relatives of mass shooting victims have been harassed and...