(CNN) -- Panamanian authorities began searching Tuesday afternoon for the bodies of five people that an American man has confessed to killing, the lead prosecutor in the case told CNN.
William Dathan Holbert, 30, and his 27-year-old girlfriend are accused of targeting people who owned property in the Bocas del Toro tourist area of Panama, said prosecutor Angel Calderon.
Holbert was using a false name and initially was identified as William Adolfo Cortez when he and girlfriend Laura Michelle Reese were arrested in Nicaragua last week, Calderon said.
Officials in Panama say the two suspects would befriend residents in Bocas del Toro and steal property from them, even killing the victims if necessary.
"He has confessed," Calderon told CNN in a telephone interview Monday night. "The main thing is that he said that once he contacted them, he would study them and would determine what class of people they were in the sense of having money, property. He would become their friend, learning very personal details.
"Later, he would eliminate them and keep their property."
Holbert has confessed to five slayings, the prosecutor said, and authorities are investigating the disappearances of five Panamanians to see if there is any connection.
Holbert has been charged with five homicide counts, Calderon said. Panama does not have a death penalty but Holbert could be sentenced to 50 years in prison, the prosecutor said.
Reese, Holbert's girlfriend, will face lesser charges related to the homicides, Calderon said.
"The charges are concrete and precise," Calderon said. "There is real evidenced that we presented, and because of that he decided to cooperate because under Panamanian law that could result in a sentence reduction."
Both suspects were traveling with false Dutch passports, Panamanian authorities said.
The pair were arrested July 26 in Nicaragua after an international hunt. They had been on the run since the body of Cher Hughes, a native of suburban St. Louis, Missouri, was found the previous week on his property in Panama.
The couple fled Panama to the north, traversed through Costa Rica and were caught as they crossed the San Juan River, the boundary between Nicaragua and Costa Rica, said Jorge Chavarria, the Costa Rican vice minister of public security.
Holbert and Reese had boarded a boat and thrown the pilot overboard, commandeering the vessel, Chavarria said. The Nicaraguan army stopped them as they tried to enter the country.
The pair were held in Nicaragua until July 28, when Panama issued an arrest warrant and they were turned over to authorities in that country. Panama sent a government airplane to pick up the suspects, Calderon said.
Holbert has asked the U.S. government for help with his legal situation, the prosecutor said. U.S. embassies abroad can offer information and general help but cannot represent citizens in legal matters.
Hughes, who was in her early 50s, was found in a shallow grave. A second body -- which has not yet been officially identified -- was found near Hughes.
Hughes had lived in St. Petersburg, Florida, where she owned a neon sign business, before moving to Panama.