Lancelot Lapahie, 25, will be sentenced to up to 10 years in prison as a condition of his plea agreement, U.S. Attorney Kenneth Gonzales said in a press release.
Lapahie admitted in federal court in Albuquerque that he attacked Ricardo Sandman with a baseball bat and George Lapahie III, Lancelot's brother, with a machete during an argument in the late hours of March 23 and early hours of March 24 at the Lapahies' home in Shiprock, according to court documents.
George Lapahie had multiple stab wounds and cuts to the head, face, forearm, leg and back and was flown to San Juan Regional Medical Center.
Sandman was treated for injuries at Northern Navajo Medical Center in Shiprock.
Lapahie was drinking alcohol prior to the attack, Gonzales said.
Police also found that Lapahie was in possession of an unregistered shotgun during the investigation, he said.
Lapahie was arrested March 24 and has been in federal custody since his arrest.
During an interview with an FBI agent on March 26, Lancelot said he attacked his brother because his brother was "talking trash" and that his brother attacked him. He also told the agent that he didn't like his brother, according to federal court documents.
Lancelot Lapahie was charged with two counts of assault with a dangerous weapon, assault resulting in serious bodily injury, child abuse and possession of an unregistered firearm.
He was charged with child abuse because he was also allegedly drinking alcohol with his younger brother, who is a juvenile, that night.
As a condition of his plea agreement, the U.S. Attorney's Office dropped the child abuse charge and one of the assault with a dangerous weapon charges.
The case was investigated by the Albuquerque and Farmington offices of the FBI and the Shiprock Division of the Navajo Nation Department of Public Safety.