Investigators search for more bombs possibly left by Austin bombing suspect

Last Updated Mar 21, 2018 7:20 PM EDT

ROUND ROCK, Texas -- While most folks in Austin, Texas were sleeping, many uneasily, the man who'd been terrorizing the city with package bombs was tracked down by the police. Twenty-three-year-old Mark Conditt killed himself with a bomb. Later, the police descended on his home in nearby Pflugerville, looking for evidence in an investigation that is far from over.

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Austin bombing suspect Mark Anthony Conditt, pictured in a 2013 photo

The manhunt in Texas for the person responsible for a series of deadly bombings came to a violent end early Wednesday morning near a Red Roof Inn just north of Austin. When police approached, investigators say Conditt drove into a ditch and blew himself up, ending the terror.

Fearing Conditt may have delivered more bombs before his death, police secured his home, knocking on doors to clear the area before sending a robot detonating device inside. Law enforcement sources tell CBS News Conditt used plastic pipe bombs packed and surrounded by nails and screws, with a simple clothespin possibly used as the triggering device. The oldest of four children, Conditt, who was homeschooled, was described by neighbors as a quiet, nerdy kid.

Police had identified Conditt from surveillance video. In the footage, a man in a blond wig can be seen entering a FedEx facility and dropping off a package. Investigators were able to close in on Conditt by following his digital fingerprint. Using sophisticated digital methods, investigators tracked Conditt's cellphone and triangulated his location.

"ATF's role in this really was to be the bomb experts and to know every single thing we could about the bombs, and all the components and where those could come from," said special agent Fred Milanowski of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) who was part of the team that pinpointed the suspected bomber.

Milanowski also said investigators found bomb parts in Conditt's Pflugerville, Texas, home that matched up with the bomb components that exploded in Austin. Investigators still don't have a motive.

Fred Burton, a counterterrorism expert, says Conditt's first mistake was getting caught on surveillance video mailing the suspicious packages.

"It's unusual to have somebody like this at such a young age," said Burton. "He was only 23, so where did he garner this kind of experience? I'm still shocked that all these devices actually worked properly because if you look at the history of serial bombers, typically you will get one or two that malfunctions."

During a news conference Wednesday night, Austin Police Chief Brian Manley said the department located a 25-minute recording on a cellphone that was in Conditt's possession. In the video, he talks about the seven bombs he constructed and describesthe differences. According to Manley, there is no mention of terrorism or hate in the video. He believes this was the outcry of a troubled man. 

"I would classify this as a confession," said Manley.

Manley said police have recovered all of the explosive devices mentioned in the recording. 

"We still want our community to remain vigilant as we always should, given the day and time in which we live now," Manley added.