It was the 26-year-old father who set off the "crazy" explosion that killed his 2-year-old son and a 66-year-old friend in Allentown, Pa., Saturday night, police say. Jacob Schmoyer allegedly used a homemade explosive device inside his car; the ensuing blast killed Schmoyer, his son, Jonathan, and his friend, David Hallman. Since the explosion, the Allentown Police Department has received four letters from Schmoyer detailing his plans to kill Hallman and his son as well as how the bomb would be made. Why? "He was miserable. Basically, the four letters describe a miserable life, he was unhappy himself," an ATF special agent told reporters Thursday, per NBC News. "He admitted to a lot of criminal acts, he didn't think it was going to get any better. There was a lot of hatred there, and obviously, some directed at Mr. Hallman and his son."
Authorities say the letters indicate Schmoyer was targeting Hallman, but also planned to take his own life and "take his son along with him," per the Allentown Morning Call. They say he "lured" Hallman out on the night of his death; surveillance video shows Hallman, who lived doors down from the location of the explosion, entering Schmoyer's car. When the explosive went off just two seconds later, Schmoyer was in the driver's seat, Hallman was in the front passenger seat, and the toddler was in a car seat in the back seat, per Lehigh Valley Live. The sister of the little boy's mom says Schmoyer also sent letters to his family before the explosion, and that they "[stated] he had something against autism, which he suspected JJ [Jonathan Schmoyer] had." Even so, Schmoyer's grandmother tells WFMZ, "I really did believe he would never do this, maybe in my heart I knew he would do it to himself, but never to JJ." (Read more murder-suicide stories.)