Mark Conditt, who was wanted for a series of bombings over three weeks that killed two people and injured several others, died after detonating a bomb in his car Wednesday as police closed in.
Police said the 23-year-old left a video recording on his phone, characterizing it as a "confession." They have not released the recording or described its contents in detail, citing an ongoing investigation.
The Austin American-Statesman newspaper, citing anonymous sources briefed on the approximately 25-minute recording's contents, said Conditt threatened more attacks.
"I wish I were sorry but I am not," Conditt said, according to the newspaper.
Conditt described himself as a "psychopath," said he had been disturbed since childhood, and threatened to blow himself up inside a crowded McDonald's restaurant if he thought he was about to be caught, the newspaper reported.
The Austin Police Department did not immediately respond to a request for comment.
Investigators are still working to determine a motive for the bombings and whether there were accomplices.
Investigators are also trying to determine how Conditt, described as an unemployed young man who had not completed college, learned to make the bombs that police said had a degree of sophistication in their construction.
Austin police chief Brian Manley told a news conference Wednesday night that Conditt did not reveal his motives on his confession tape, but did describe all of the seven package bombs that he had built.
"What is clear from listening to that video, is this was a very troubled young man who was talking about challenges in his life that led him to the point where he took the actions that he took," Manley said.
"And there were also indications of actions he was willing to take in the future," he added.
The bombings that began on March 2 terrorized Austin -- a city of nearly one million people. Hundreds of federal and local law enforcement officers conducted a massive manhunt to find the bomber.
A major break came when Conditt shipped two explosive packages via an Austin FedEx office, allowing authorities to capture enough information to identify a suspect.