Authorities: Man sent letters before car blast that killed 3

Authorities: Man sent letters before car blast that killed 3
FILE - In this Monday, Oct. 1, 2018 file photo, authorities investigate the scene of Saturday's fatal car explosion in Allentown, Pa. Officials with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives are holding a news conference Thursday, Oct. 4 with prosecutors and Allentown police.(AP Photo/Matt Rourke, File)

ALLENTOWN, Pa. (AP) — Investigators are expected to reveal the cause of a car explosion in Allentown, Pennsylvania, that killed three people, including a father and his toddler son.

Officials with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives are holding a news conference Thursday with prosecutors and Allentown police. They’re expected to discuss the contents of letters that 26-year-old Jacob Schmoyer sent before the weekend blast that killed Schmoyer, his 2-year-old son Jonathan “JJ” Schmoyer and a friend, 66-year-old David Hillman.

The explosion scattered debris and body parts over several city blocks.

Schmoyer’s grandmother, Kathleen Pond, told WFMZ she received a letter. She did not reveal what he wrote, but told the station: “Maybe in my heart I knew he would do it to himself, but never to JJ.”