A father who gifted his 14-year-old son an assault rifle that the teenager then used to unleash a mass shooting at a Georgia high school was sentenced Thursday to 15 years in prison. Investigators said he had become particularly fixated on the perpetrators of the 1999 Columbine High School shooting in Littleton, Colorado, and the 2012 Sandy Hook Elementary School shooting in Newtown, Connecticut. Those killed in the Apalachee High School shooting were students Mason Schermerhorn and Christian Angulo, both 14, and teachers Richard “Ricky” Aspinwall, 39, and Cristina Irimie, 53. Aspinwall’s wife, who is also a high school teacher, condemned him for failing to be a “responsible gun owner.” Hobbs also suggested that the teenager’s mother, Marcee Gray, bore more responsibility than his client for fostering his obsession with school shooters.