Benally and his co-defendant, Luke Spencer, 48, who also resides in Gallup, were indicted in March 2012.
Count 1 of the indictment charged Benally with second-degree murder and Count 2 charged Spencer with aiding and abetting second-degree murder.
According to the indictment, Benally, who was aided by Spencer, killed a man while driving under the influence of alcohol on the Navajo Nation between Oct. 1 and Oct. 2 in 2010.
During the hearing, Benally entered a guilty plea to second-degree murder and admitted that on the night of Oct. 1, 2010 or early hours of Oct. 2, 2010, he drove Spencer's truck despite being severely intoxicated.
While backing up, Benally ran over a 71-year-old Navajo man. Benally further admitted that he and Spencer, who was in the passenger's seat, drove away in the truck without making any effort to check on the victim's condition or calling the authorities to report the accident.
The victim died of injuries he sustained and his remains were found by a passerby on Oct. 7, 2010.
Under the terms of the plea agreement, Benally will be sentenced to a prison term within the range of 10 to 12 years followed by a term of supervised release to be determined by the court. Benally has been in federal custody since his arrest on March 13, 2012 and remains detained pending his sentencing hearing, which has yet to be scheduled.
On May 28, 2013, Spencer entered a guilty plea to a felony information charging him with involuntary manslaughter for permitting Benally to drive his truck while intoxicated.
At sentencing, Spencer faces a maximum penalty of eight years in prison. Spencer remains in the custody of the U.S. Marshals Service pending his sentencing hearing, which has not yet been scheduled.
Counselors man sentenced for manslaughter
Harlen Sam, 34, who resides in Counselors, N.M., was sentenced Monday to 46 months in federal prison followed by three years of supervised release for his involuntary manslaughter conviction.
In Dec. 2012, Sam entered a guilty plea to two counts of involuntary manslaughter and admitted causing the death of two passengers in his vehicle on May 4, 2012, when he crashed while driving under the influence of alcohol.
The crash occurred on a dirt road about four miles east of the Ojo Encino Chapter House.
Court records reflect that on May 4, 2012, Sam was driving a vehicle with four adult and five child passengers when he crashed the vehicle. An elderly woman and a four-year-old boy died after being ejected from the vehicle during the crash.
In his plea agreement, Sam admitted he was driving while intoxicated when he crashed and caused the deaths of the two victims. Sam also acknowledged that his blood alcohol level was .08 when his blood was drawn within three hours of the collision.
Sam has been in federal custody since his arrest on May 4, 2012.
Murder, sex charges dropped
The case against a St. Michaels man accused of murdering a woman from Church Rock, N.M in Gallup in 2010 has taken a strange twist.
Officials for the McKinley County District Attorney's Office said Monday that they have decided to drop murder and criminal sexual penetration charges against Adrian Miles, 23.
Miles was arrested for the September 10, 2010 murder of Sheila Knapp at the Ambassador Motel in Gallup.
Miles has agreed, however, to plead guilty to false imprisonment and tampering with evidence and the district attorney's office has agreed to cap any sentence he would receive on those charges to no more than two years in prison.
Knapp's body was discovered on the upper level of the motel on Sept.8 by Miles and his girlfriend. She was nude and had blood on her face. She died two days later without regaining consciousness.
Miles was arrested when a rape kit discovered DNA evidence that was linked to Miles or any of his paternal relatives.
Miles admitted that Knapp spent part of the night in the room with him and his girlfriend but said that she slept on the floor after he saw her outside in the rain without any clothes on arguing with her boyfriend.
The case, which has been in the court system for more than two years, centered on the likelihood that this was Miles' DNA sample in the rape kit.
But DNA experts during depositions pointed out that because of unique situations within the Navajo population in which they married for generations within the tribe, people other than paternal relatives of Miles could also be a match.
One expert said that as many as one in four Navajo men could be a match for that DNA sample.
Lyndy Bennett, chief deputy district attorney, said that a decision was finally made that there was "insufficient evidence to prove the case (against Miles) beyond a reasonable doubt."
Mile's formal sentencing is scheduled for August 12 in McKinley County District Court.