The devices used in the Austin and San Antonio-area explosions were pipe bombs with batteries and smokeless powder and were constructed with materials found in a hardware or sporting goods store, a law enforcement source with knowledge of the investigation told CNN.
The homemade bombs used by Mark Anthony Conditt had distinctive shrapnel inside, according to the law enforcement source.
The source also told CNN that some bombs had "mouse trap" switches and others had "clothespin" switches, each with distinctive springs that made them identifiable even after a blast, the source said.
The tension on these switches could be adjusted, and the bombs were meant to go off to kill people.
Police said Conditt, 23, began placing bombs in packages outside people's homes on March 2. Conditt also used a trip wire across a sidewalk to trigger another bomb. The package in the San Antonio-area went off on a conveyor belt at a FedEx facility in Schertz.
Conditt died in his car Wednesday morning when he set of one of his devices. A SWAT officer was injured by the blast.
Conditt was responsible for five previous explosions in Texas this month that killed two people and injured five others, police said.