Lockhart tried to flee Phenix City police after being pulled over Friday, Auburn Assistant Police Chief Thomas Dawson said.
"His car matched the description of a vehicle in a string of robberies," Dawson said. When an officer approached the car at the traffic stop, Lockhart drove off, Dawson said.
In a short pursuit, Lockhart's car broke down and he was captured by officers while trying to flee on foot, Dawson said.
Lockhart, 23, was charged with three capital counts accusing him of murder along with kidnapping, robbery and attempted rape, Dawson said.
He wouldn't say what led police to charge Lockhart in the student's killing or divulge evidence linking Lockhart to that crime.
Dawson said investigators have a photo of the suspect that was enhanced with the help of NASA, but he wouldn't say how the photo was obtained.
"We have the right individual in jail, I'm 100 percent sure of that," Dawson said.
Investigators don't believe Lockhart had any connection to Auburn University or that he knew Burk before abducting her.
"I don't believe he targeted her that long, if he targeted her at all," Dawson said.
Lockhart, from rural Smiths in Russell County, was in custody Saturday with bail set at $250,000, Dawson said. He may still be charged with robberies, Dawson said. There was no immediate word if he had a lawyer to speak for him; if he is indigent, a lawyer could be appointed at a Lee County Circuit Court hearing Monday in Auburn.
Burk, of Marietta, Ga., was a member of the Delta Gamma sorority. Auburn University planned a campus-wide memorial service for her Monday.
Auburn Police Chief Frank deGraffenreid said the increased police presence on campus that began after the shooting will continue indefinitely to "help calm some fears and anxieties of parents."
Alysha Kambeyanda said she still felt safe at her school and hoped that the tragedy will remind fellow students to be more aware of their surroundings.
"I think the people on campus need to be safer with what they do, make smarter decisions about where they go," she said. "I've seen girls running alone at night, listening to their iPods. That doesn't seem like a good idea."
Police in North Carolina, investigating the killing of a university student there, had been in contact with Alabama authorities investigating Burk's killing. However, officials said the cases did not appear to be connected.
In North Carolina, police released two surveillance photos of the suspect in Eve Carson's killing, taken as the man used her ATM card in Chapel Hill. Another photo of the suspect's baseball cap was also released.
Carson, 22, of Athens, Ga., was found Wednesday morning lying on a street about a mile from campus. She had been shot several times, including once in the right temple.
She appears to be the victim of a random crime, authorities said.