Israel Mireles, 24, was arrested on a Butler County homicide warrant in Melchor Muzquiz, Mexico, southwest of Texas. He was being held there pending extradition, U.S. Deputy Marshal Logan Kline said.
Mireles has been charged with capital murder, rape and aggravated criminal sodomy in the death of 18-year-old Emily Sander, Butler County prosecutor Jan Satterfield said.
Sander was last seen alive on Nov. 23 when she left an El Dorado bar with a man police identified as Mireles. The disappearance of the Butler Community College student drew nationwide attention after the discovery that she also led a secret life as an Internet pornography model named Zoey Zane.
Her body was found six days later, about 50 miles east of El Dorado, as police traced the route they believed Mireles took to pick up his 16-year-old girlfriend, Victoria Martens, in Baxter Springs.
Kansas authorities received tips about Mireles' whereabouts in Mexico from several sources, and their Mexican counterparts had been monitoring his movements since at least Dec. 3, when he was charged in Butler County, she said.
Mexican authorities held off on arresting Mireles until they were assured of the legitimacy of Kansas prosecutors' case, Satterfield said.
Satterfield said her office had to promise Mexican authorities that it would not seek the death penalty for Mireles. If convicted of capital murder, he would face life in prison without the possibility of parole, she said.
U.S. Marshal Troy Oberly said Martens, who is eight months pregnant, was found unharmed in Mexico but has refused to return to Kansas. Satterfield said prosecutors don't plan to file charges against her.
"It doesn't sound likes she wants to return to the U.S. Our main concern was that she was alive and safe," Oberly said.
Mireles became the focus of the investigation after police found large quantities of blood in an El Dorado motel room where he had been staying. Authorities have said that a bedspread that was missing from that motel room was found close to Sander's body.
Police have not released details about the cause of Sander's death, but say her Internet activity had no connection to her disappearance.
Mireles was born in Mexico, where he still has relatives, and has been living in the U.S. legally. A rental car he was driving was found Nov. 27 in Texas, where he also has relatives.