In an audio recorded cellphone statement,said: "I wish I were sorry but I am not" for the deadly attacks, according to a person familiar with the matter. During the more than 25 minute statement, Conditt described himself as a "psychopath" and said he feels as though he has been disturbed since childhood, a person confirmed to CBS News' senior investigative producer Pat Milton.
Conditt also promised he would go inside a crowded McDonald's and blow himself up if he thought authorities were closing in on him.
He blamed himself for helping investigators find him by going into the FedEx store to mail explosive devices allowing him to be videotaped by store cameras and allowing them to get his license plate.
He gave no information on how he chose his targets but acknowledged his actions left family members without loved ones and caused permanent injury to others. He made the audio recording around 9 p.m. Tuesday night.
The Austin American-Statesman was the first to report the contents of the audio statement, which was confirmed for CBS News by a person familiar with the matter.
Interim Austin police Chief Brian Manley publicly disclosed the existence of the cellphone audio at a new conference Wednesday but provided limited details on the statement which he referred to as a confession. Manley described Conditt's statement as "the outcry of a very challenged young man."
Conditt allegedly killed two people, identified as Anthony Stephan House and Draylen Mason, and wounded five others with a series of bomb attacks that terrorized the Austin area for the past month.
after a bomb detonated inside his car as officers closed in on him to arrest him early Wednesday morning.
Conditt was described Wednesday by his uncle as a smart and kind "computer geek" and a friend said he was an assertive person who would end up being "kind of dominant and intimidating in conversation."
Neither had any idea what might have motivated him to carry out the attacks in the Texas capital and suburban San Antonio.
"I mean this is coming from nowhere. We just don't know what. I don't know how many ways to say it but everyone is caught off guard by this," Conditt's uncle, Mike Courtney of Lakewood, Colorado, told The Associated Press.
Manley suggested that there might never be a clear motive, noting where the explosives were placed or addressed seems random. CBS affiliate KEYE-TV reports that a package dropped off at FedEx by Conditt on Sunday was labeled as being sent by "Kelly Killmore" to an address in South Austin that does not exist. The package was found by law enforcement on Tuesday and did not explode.
Conditt grew up in Pflugerville, a suburb just northeast of Austin where he was still living just a few miles from his parents' home after moving out. On Wednesday, authorities recovered homemade explosives from inside the residence, which he shared with roommates.
Conditt's family said in a statement they had "no idea of the darkness that Mark must have been in."
Conditt was the oldest of four children who were all home-schooled.
Although he worked for a time at an area manufacturing company, Gov. Greg Abbott told KXAN-TV in Austin that Conditt apparently was unemployed more recently and had no criminal record.
Conditt left little discernable trace on social media. Aside from a few photos of him on his family's Facebook pages, he addressed a range of topics in an online blog he created in 2012. Vess said he had created the blog as part of a U.S. government class project.
In the blog titled "Defining my Stance" he gives his opinion on several issues, often in response to commentary by someone else. Conditt wrote that gay marriage should be illegal, argued in favor of the death penalty and gave his thoughts on "why we might want to consider" eliminating sex offender registries.
Of gay marriage, Conditt wrote: "Homosexuality is not natural. Just look at the male and female bodies. They are obviously designed to couple."
In the "about me" section of the blog, Conditt wrote that he wasn't "that politically inclined," saying he viewed himself as conservative but didn't think he had enough information "to defend my stance as well as it should be defended." He said he hoped the class would help him do that.