FLAGSTAFF, Ariz. (AP) – Federal authorities on Tuesday charged an Arizona man with first-degree murder in the weekend shooting of a Navajo Nation police officer in one of the reservation’s communities.

Victor Bigman, 48, of Kaibeto, was charged by criminal complaint in the death of Sgt. Darrell Curley, who had responded to a report of Bigman’s sons drinking alcohol and fighting at their parents’ home late Saturday.

Curley was forced to use pepper spray when the brothers resisted arrest and was taking one of them to his patrol vehicle when Bigman grabbed a weapon and fired four shots, authorities said.

Curley returned fire, wounding Bigman. Authorities said Curley, 48, died hours after the shooting while Bigman remained hospitalized in critical condition Tuesday.

“We are deeply saddened by the death in the line of duty of Sgt. Darrell Curley,” said Arizona U.S. Attorney Dennis Burke. “Our thoughts are with his family and colleagues as we work diligently to advance this murder investigation and seek justice for this incomprehensible crime.”

Johnson Bigman, 25, and Tyson Bigman, 21, pleaded not guilty Monday to tribal charges of disorderly conduct, homicide, accomplice to aggravated assault and criminal nuisance. They remain in tribal custody pending a Friday bail hearing in Tuba City.

The brothers do not have an attorney listed with the Navajo Nation courts, said Karen Francis, a spokeswoman for the tribe’s judicial branch.

Telephone numbers listed for their parents were disconnected or went unanswered Tuesday, and the tribe’s public defender’s office said it had not been appointed to represent them.

The FBI and the Navajo tribe have concurrent jurisdiction when both the suspect and victims of an alleged crime are American Indian. Tribal authorities can prosecute only misdemeanors that typically carry far lighter sentences than federal convictions. Victor Bigman faces life in prison if convicted on the federal charge.

The Arizona Department of Public Safety assisted in the investigation because the shooting involved a police officer.

Bigman’s wife, Gloria, twice called Navajo police saying her sons were fighting. Curley and Navajo police Officer Vernon Begay responded in separate patrol vehicles, according to the federal complaint. Begay arrived first but did not approach the brothers until Curley arrived because he was concerned about their demeanor.

Tribal and federal complaints show the brothers were largely uncooperative. Tyson Bigman swung his fists at Curley at one point, and Victor Bigman stood between Curley and his son to prevent him from being detained, federal authorities stated.

Begay told authorities that he heard two gunshots as he was placing Johnson Begay in his patrol vehicle, turned and heard two more pops. Begay said he then saw Curley shoot a single round before falling on his back, the complaint states. A 9 mm semi-automatic pistol was found underneath Victor Bigman, the federal complaint states.

Begay was treated and released at the scene, tribal officials said.

Complaints filed against the brothers Monday in Tuba City District court offer a far briefer version of the events and say little about the circumstances of the shooting.

An autopsy showed that Curley was hit once twice in the left shoulder, with one shot damaging his lung. A protective vest stopped the other two shots from penetrating his body.

Curley was promoted to sergeant in 2003 and assigned to the tribe’s Tuba City district that includes Kaibeto. He first joined the police force in 1986.

Tribal officials, including Navajo President Ben Shelly, Tribal Council Speaker Johnny Naize and director of public safety John Billison, praised Curley for his commitment to ensuring safety in tribal communities. Flags were ordered flown at half-staff across the Navajo Nation through Thursday.

“Sgt. Curley proudly served on behalf of not only his family but for the tribe, and he has done so with great dedication, honor, integrity and respect for all,” Billison said in a statement.

Funeral services are scheduled Saturday in Curley’s hometown of Chinle, according to Naize’s office.