ROUND ROCK, Texas (AP) - A federal agent says it's "hard to say" whether the dead suspect in this month's Austin bombings was acting alone.
Fred Milanowski, agent in charge of the Bureau of Alcohol, Tobacco and Firearms' Houston Field Division, told reporters Wednesday that investigators believe the dead suspect built all of four of the package bombs that have blown up in Austin since March 2.
Authorities say the 23-year-old suspect, Mark Anthony Conditt, blew himself up in his vehicle overnight as a SWAT team closed in on him in a suburban Austin hotel parking lot.
Milanowski says investigators aren't completely convinced that there aren't other explosive devices "out there," and that they want the public to remain vigilant.
He called the bomb that killed the suspect "a significant explosive device."
Asked if the suspect built bombs prior to the start of the spree in Austin, Milanowski responded: "We know when he bought some of the components. It's hard to say whether he was building along the way."
This story has been updated to include the suspect's name and correct his age from 24 to 23.