AUSTIN — The FBI agents and police investigators tasked with identifying who was responsible for planting a series of bombs here seemed at times to be chasing ghosts.
They ran down theories of drug dealer retaliation gone awry, and struggled to understand the significance of family connections between the victims. All the while, the bomber escalated his attacks – first using a trip wire, and then by sending explosives through FedEx.
But behind the scenes, investigators had used cell tower data to tie Mark Anthony Conditt, a 23-year-old from the Austin suburbs, to the bombing sites and other important locations, the Texas governor said Wednesday. And when the suspected bomber used FedEx, law enforcement caught an ever bigger break: He had been captured on a store's video surveillance system.
The furious manhunt for Conditt culminated early Wednesday morning after one of the police surveillance teams scouring the area spotted his red SUV in a hotel parking lot in Round Rock, Texas, about 18 miles north of the Texas capital.
Officers closed in, and Conditt ultimately detonated a bomb and was killed. The bloody confrontation brought an end to three weeks of terror in which investigators believe Conditt planted at least six bombs either at homes or in the FedEx delivery system. The devices killed two people and injured several others, and officials warned he could have left more bombs elsewhere that have yet to be found.
"This is the culmination of three very long weeks for our community," said Austin Police Chief Brian Manley, adding, "We don't know where this suspect has spent his last 24 hours, and therefore, we still need to remain vigilant to ensure that no other packages or devices have been left through the community."
On Wednesday, FBI officials searched Conditt's home for clues about what might have motivated the attacks as they advised Austin residents to remain wary. They took two of his roommates into custody for questioning – though they released one and said neither was under arrest. A neighbor to a home owned by the Conditt family said an officer with a megaphone had yelled that the FBI was there with a search warrant, and a young man came out of the house and was immediately handcuffed and led to an unmarked SUV.
Conditt attended Austin Community College between 2010 and 2012 but did not graduate, according to the school. Mark Roessler, 57, a neighbor, described Conditt as "quiet, introverted, polite and clean-cut," adding that he never had a lot of visitors, loud parties or other social events.
He said he last saw Conditt about a week ago, when they both arrived home at the same time. "We didn't make eye contact," Roessler said. "In retrospect, he was certainly in the midst of all of this."
Eddie Harp, who has been friends with the Conditt family for 15 years, read a short statement to the media outside the Conditts' home, saying: "I have a simple and heartfelt statement from the family. This will be their only statement. The family is grieved not only for their loss for but also for the loss of those affected by these heinous actions. The family's present focus is on dealing with their shock and loss and cooperating with the police investigation. If you are a praying person, please join us in praying for the families of all who have lost loved ones."
Law enforcement officials said they had no idea what might have triggered him to carry out the bombings, but Texas Gov. Greg Abbott, R, said he expected they would find a "treasure trove of information" inside Conditt's home. Agents have found components that match materials used in the bombs inside the suspect's house but not completed bombs, officials said.
The ATF has been able to reconstruct all the bombs he made. "We know it's the same person who manufactured all of these," said ATF Deputy Assistant Director Fred Milanowski.
Conditt had been an enigma to law enforcement. After the first explosion killed 39-year-old Anthony House on March 2, police were reluctant to even call the episode a homicide and said they believed the incident was isolated.
"We can't rule out that Mr. House didn't construct this himself and accidentally detonate it, in which case it would be an accidental death," Assistant Chief Joe Chacon said in the days after the incident.
Investigators at first explored a theory in which House might have been the unintended recipient of a bomb meant for a drug dealing neighbor. Austin police had recently raided a home nearby, and seized marijuana and hundreds of thousands of dollars, according to an attorney for the man who lived there.
The attorney, Mark McCrimmon, said investigators asked his client, who he declined to identify, to come in for an interview on the day the bomb went off. They seemed convinced that the bomb was meant for his client, and tried to play "good cop, bad cop," McCrimmon said, asking him, "Who's trying to kill you?" and warning him that his roommate might be in danger.
"They used the C-word, cartel, and we kept saying, it's not a cartel, it's not a cartel, it's not a cartel," McCrimmon said. "It's just pot, and it's the cost of doing business sometimes."
He added: "They're scrambling, and they come across a pretty good lead. I don't blame them for giving us the bright light treatment."
When two more bombs went off 10 days later, investigators rapidly shifted gears. More than 350 law enforcement personnel – including FBI behavioral analysts and ATF forensic scientists – soon descended on Austin.
They explored family ties between House and the second victim, 17-year-old Draylen Mason, and whether the episodes might have been racially motivated. House's stepfather and Mason's grandfather were close friends and both prominent members of Austin's African-American community. They wondered whether that made them targets.
Investigators also explored whether the third bomb, which injured a 75-year-old Hispanic woman, might have been meant for someone else, interviewing a woman who lived on the block with the last name Mason, though she was of no relation to Draylen.
"The federal government brought the full resources of federal law enforcement here to solve this and to stop the injuring and the killing that was occurring," FBI Special Agent in Charge Christopher Combs said Wednesday.
The bombs, though, continued. A device activated with a trip wire injured two people, and investigators then discovered two packages that had been sent through FedEx. One of the packages exploded at a FedEx facility in Schertz, Tex., while the other was recovered from a different facility in Austin.
The company turned over that package and extensive information, including surveillance footage, to law enforcement, which would prove to be critical.
"That proved to be the case," Austin Mayor Steve Adler, D, said early Wednesday.
Abbott, the Texas governor, said officials tied Conditt to the explosions first by his cellphone – which they were able to detect was at the bombing sites. He said investigators then determined that Conditt's red SUV had been at "various locations that tied him, possibly, to those crimes."
The FedEx surveillance footage, from a south Austin store, showed Conditt wearing a wig and gloves, and officers soon obtained a receipt for the disguise, Abbott said. He said they also determined that Conditt purchased signs, like the one used to anchor the tripwire that triggered an explosion, at a Home Depot in the town of Pflugerville.
Manley, the Austin police chief, said investigators became "very interested" in Conditt "over the past couple of days."
Federal prosecutors already had charged Conditt with one count of unlawful possession and transfer of a destructive device by the time officers spotted him in his SUV.
Police said officers surrounded the hotel to take him into custody, and he started to drive away. He then pulled his vehicle over on the side of a frontage road of Interstate 35, officials said.
As a SWAT officer approached the SUV, Conditt detonated a bomb inside his car, injuring one officer. At that point, another officer fired at the suspect, police said. They found Conditt dead inside the vehicle with severe injuries from the bomb, officials said.
Frank de la Fuente, who was staying at a Red Roof Inn on Highway 35, said he heard an explosion at about 3:30 a.m. followed by two gunshots.
Jeremy Lowe, who was also staying at the Red Roof Inn, said that "they shut down the highway and told everybody to not go anywhere."
While investigators continued to explore whether someone might have worked with Conditt – or whether he left the potential for more destruction behind – some said his arrest brought some reassurance.
"I'm relieved for the people of this state and the city of Austin to know that the person who was the author of this horrific destruction and harmed lives no longer poses a danger," Abbott said.
President Donald Trump wrote on Twitter: "AUSTIN BOMBING SUSPECT IS DEAD. Great job by law enforcement and all concerned!"
Barrett, Zapotosky and Berman reported from Washington. Kristine Phillips in Austin contributed to this report.