March 22 (UPI) -- The Austin, Texas, bomber left behind an audio recording that described his explosive devices and a "hit list" of sorts for potential targets, authorities said.
Bombing suspect Mark Conditt died early Wednesday in Round Rock, Texas, after setting off an explosion as police approached his sport-utility vehicle, according to investigators.
"If we had not found this man, there would have been more devices, and more innocent civilians would have been hurt and been killed," FBI Special Agent Christopher Combs told the Los Angeles Times.
As investigators try and piece each crime scene together, more is being learned about the young man behind the crimes that terrorized Austin over the last month.
A statement by Conditt's family said they were stunned and "broken" that he was behind the deadly bombings.
"We are devastated and broken at the news that our family member could be involved in such an awful way," the family said in a statement.
"We had no idea of the darkness that Mark must have been in. Our family is a normal family in every way. We love, and we pray and, we try to inspire and serve others. Right now our prayers are for those families who have lost loved ones, for those impacted in any way, and for the soul of our Mark. We are grieving, and we are in shock. Please respect our privacy as we deal with this terrible, terrible knowledge and try to support each other at this time."
Police say the cellphone recording left behind by the suspected serial bomber described the devices used in the bombings.
In the 25-minute recording suspect Mark Conditt described the seven devices used including the four that exploded in Austin, one that detonated at a FedEx facility in Schertz, one retrieved from a FedEx facility in Southeast Austin unexploded and the one he detonated in his car as he killed himself Wednesday, Austin interim police Chief Brian Manley said.
"I would classify this as a confession," Manley said.
Manley added the suspect didn't provide a reason for why he targeted the people who were killed or injured in the attacks.
"We are never going to be able to put a rationale behind these acts," Manley said.
Earlier Wednesday authorities found additional explosives and bomb-making components during a search of Conditt's home.
ATF Special Agent in Charge of Houston Field division Fred Milanowski said they found no completed explosive devices at Conditt's Pflugerville, Texas, home. Police cleared a five-block radius around the residence as they searched.
Milanowski said there was a high degree of certainty the components they found in Conditt's residence were the same used in six bombs used throughout the month -- one did not detonate.
Police said several related bombings this month were the work of Conditt -- who changed tactics as he left explosive packages around Austin, beginning March 2. Another went off at a FedEx sorting facility near San Antonio on Tuesday. Two people died in the string of attacks and multiple others were injured.
Using surveillance video from a FedEx store in south Austin, investigators keyed in on Conditt, who they tracked to a hotel in Round Rock, about 15 miles northeast of the Texas capital.
Police said they surveilled the suspect in his vehicle Wednesday while awaiting a SWAT team. Officials said when he left the hotel around 2 a.m., police followed and pulled him over on Interstate 35. When SWAT officers approached the vehicle, he set off a bomb -- killing himself and injuring an officer.
The suspect was home-schooled and described as "a deep thinker" who came from a tight family, according to those who knew him.
A neighbor told reporters despite sounding cliché, he "was a nice kid from a great family." According to an Austin Community College spokesperson, the suspected bomber attended the college from 2010 to 2012 but did not graduate.