A federal grand jury has charged Brendt A. Christensen, the suspect in the kidnapping of visiting Chinese scholar Zhang Yingying, with kidnapping resulting in death, the media reported.
The US Justice Department said Christensen, if convicted, could face mandatory life in prison or even death penalty.
The grand jury on Tuesday said Christensen committed the offence "in an especially heinous, cruel or depraved manner after substantial planning and premeditation to cause the death of a person", according to the four-page indictment obtained by Xinhua news agency.
Christensen was previously charged with kidnapping Zhang on June 9. The superseding indictment by a federal grand jury added the charge that kidnapping resulted in Zhang's death.
He could face death penalty on the new charge. If the prosecutors decide not to seek death penalty, a conviction would result in mandatory life in prison without parole.
He was also charged with two counts of making false statements to the Federal Bureau of Investigation (FBI) agents. This could result in five years in prison on each charge if convicted.
He is currently being held without bond with the tentative schedule to go on trial before US District Court Judge Colin Bruce on February 27, 2018.
Zhang went missing on her way to sign a lease on June 9. Investigators later announced that she was kidnapped. Prosecutors allege that Christensen approached Zhang and lured her into his car.
According to surveillance footage, the law enforcement agents first turned their attention to Christensen after they found his car was the same one Zhang disappeared in.
Christensen, however, told the FBI that he was at home all day on the day Zhang went missing.
He then changed his story, saying that he came across an Asian woman and offered her a ride. Christensen added that he let her out of his car after she panicked.
The FBI conducted audio surveillance on Christensen which produced enough evidence to lead to his arrest on June 30.