JACKSONVILLE, North Carolina (CNN) -- A prosecutor said Friday that he is confident U.S. Marine Cpl. Cesar Laurean will waive extradition in Mexico and "be back in North Carolina sooner than later" to face charges including murder.
Onslow County (North Carolina) District Attorney Dewey Hudson did not elaborate.
But at a news conference later Friday, he said, "Depending on how he deals with extradition, [it] could take a couple days or couple of years."
Hudson later said it would take at least 60 days for U.S. authorities to file with the Mexican government the necessary paperwork seeking to extradite Laurean.
Laurean, a suspect in the killing of a 20-year-old pregnant Marine, was captured Thursday night in Mexico. Watch authorities discuss the arrest »
U.S. authorities want to bring Laurean back to the United States to face murder charges in the killing of Lance Cpl. Maria Lauterbach.
Onslow County Sheriff Ed Brown said Laurean was captured much sooner than he had expected, and he praised the three-month international effort to apprehend the 21-year-old Marine, who fled North Carolina in January.
"Mistakes? We made none; he did, and he's captured," Brown said.
Mexican authorities said they arrested Laurean in San Juan Vina in the state of Michoacan.
He was taken to Mexico City, where Mexican federal authorities were questioning him Friday afternoon, the U.S. Embassy in Mexico said. Watch Laurean after his capture »
He was taken into custody after he walked up to a roadblock set up by a local anti-kidnapping task force investigating another case, according to Magdalena Guzman of the Michoacan state attorney general's office.
The man gave authorities his real name, and they entered it into a criminal database that alerted them to his fugitive status, Guzman said.
Asked whether Laurean was caught by accident, Brown said, "I know what's been going on behind the scenes. ... I'm confident in saying the reason Cesar Laurean is in custody is by the professional pursuit that the agencies, all agencies involved, have carried on from the time he left here."
Brown added, "He has to be lucky every day; we have to be correct one day."
In recent weeks, authorities found out that Laurean was trying to communicate with family members and others in North Carolina, said Capt. Rick Sutherland of the Onslow County sheriff's office.
"We were able to narrow our focus" based on that information, he said.
Authorities said Laurean killed Lauterbach December 14 and used her ATM card 10 days later before fleeing to Mexico.
In January, Lauterbach's charred body and that of her fetus were found beneath a fire pit in Laurean's backyard in Onslow County.
He has been indicted on charges of murder, ATM card theft, attempted card theft, fraud and robbery with a dangerous weapon. See a timeline of events »
Since Laurean holds both U.S. and Mexican citizenship, he cannot be immediately deported, Guzman said. His Mexican citizenship requires an extradition hearing.
His capture in Mexico protects Laurean from facing the death penalty in the United States. Mexico's extradition policy prohibits U.S. officials from seeking capital punishment against fugitives turned over by Mexican authorities.
Brown said that when Laurean is returned to the U.S., he'll be treated like any other prisoner in Onslow County's jail.
The sheriff also said he had both the Laurean and Lauterbach families in his prayers.
Authorities found Lauterbach's body after Laurean's wife produced a note from Laurean saying Lauterbach slit her throat during an argument, according to officials. A 4-inch wound was found on the left side of Lauterbach's neck, but autopsy results indicate that the wound would not have been fatal.
A law enforcement official said federal authorities recently seized a computer belonging to Laurean's sister-in-law, which his wife was using to communicate with him while he was on the run. Laurean apparently told his wife in e-mails that he wanted to return to the United States, the official said.
Authorities also seized the wife's diary, the official said.
On Friday, Hudson emphasized that there was no evidence that Laurean's wife, Christina, was involved in or aware of the slaying before reporting information to authorities.
"She did not help with the murder and did not help him bury the body," he said.
Sutherland said that Christina Laurean denied her husband's request for resources while he was on the lam and that her communication with him did not violate North Carolina law.
Lauterbach's mother, who said that she was "still in shock" that Laurean had been captured, said Friday that she thinks Laurean is probably her daughter's killer. Watch the victim's mother describe her reaction to the capture »
"Of course, I'm a great believer, too, in the American system of justice where you have a presumption of innocence until proven guilty. But in my heart of hearts, I do believe he is," Mary Lauterbach said. "I want the truth to come out. And the American legal system to work as it always has."
She said she also believes that Laurean is the father of her daughter's fetus.
Lauterbach said that if she saw Laurean, "I would say to him, 'I pray for you, and I pray for your family, and I hope at this point you can begin to be honest about what actually happened.' "
Maria Lauterbach had accused Laurean of raping her. He denied the allegation and any sexual contact with her.
"I loved her," Laurean said Thursday night when a Mexican reporter asked whether he killed Lauterbach. E-mail to a friend
CNN's Susan Candiotti, Joe Duran and Harris Whitbeck contributed to this report.