Teen found guilty of lesser charges in shooting deaths of 2 students at Iowa school

Preston Walls claimed he shot in self-defense and was convicted of second-degree murder and manslaughter.
Walls killed 2 students, Gionni Dameron and Rashad Carr, and injured the founder of the school program.
Walls avoided a mandatory life sentence by being convicted of lesser charges.
Walls will be sentenced in November while another person awaits trial for murder charges.
The shootings happened at an alternative school in Des Moines, Iowa.