Local retired explosives expert analyzes Boston Marathon bombing

Local retired explosives expert analyzes Boston Marathon bombing »Play Video

In this Monday, April 15, 2013 photo, emergency personnel carry a wounded person away from the scene of an explosion at the 2013 Boston Marathon in Boston. Two explosions shattered the euphoria of the Boston Marathon finish line on Monday, sending authorities out on the course to carry off the injured while the stragglers were rerouted away from the smoking site of the blasts. People across the country echoed strains of defiance, tenderness and wariness as Americans try to make sense of Boston bombings. (AP Photo/Kenshin Okubo)

HORSESHOE BEND - An explosives expert who worked in New York City and now lives in Horseshoe Bend spoke to KBOI 2News within hours of last week's explosions at the Boston Marathon and says he believes one person may have been the explosives designer.

Larry Ostrowski was an explosives detective in the Big Apple between 1994 and 2000.

He says FBI agents in Boston are looking for a "signature build" in each device, examining what they're made of and how they're assembled.

He says the agents have a lot to go on.

"What do they see at the blast site? What type of materials are remaining at the blast site? An explosive device, when it does detonate, leaves certain undetonated materials," Ostrowski said via phone from Horseshoe Bend.

He believes someone was planting explosives shortly before the marathon began, but ran into large crowds, and had to abandon some of the plan.