Gabriel Alcon, 23, entered an Alford plea to second-murder in the death of Jacquez, 32, and pleaded guilty to a drug-trafficking charge. The agreement covers both charges.
An Alford plea allows a defendant to accept a plea agreement without admitting guilt.
Alcon was scheduled to go to trial on Monday to face a murder count, as well as drug trafficking, conspiracy and tampering with evidence charges.
"A cap of 10 years is the big deal here," said Alcon's attorney, Eric Morrow. "He still maintains his innocence on the murder charge."
The bizarre circumstances of the case included an escalating verbal fight, a claim that Jacquez intended to kill or maim another person before he was shot, and an attempt to hide the incident by dumping Jacquez's body and burning a car involved in the incident.
District Judge William Birdsall said he will wait to accept the plea agreement until Alcon's sentencing hearing, which has not been scheduled. If Birdsall rejects the agreement, Alcon could go to trial on the charges.
Jacquez was shot five times in the back of the head after midnight on May 27, 2012.
Sarah Martinez, an Aztec woman, was giving Jacquez a ride home from a party at her home on County Road 2595.
Jacquez was sitting in the front passenger seat and Alcon was sitting behind him, San Juan County Chief Deputy District Attorney Brent Capshaw said.
Both the defense attorney and DA agreed that at some point during the ride Alcon shot Jacquez five times in the back of the head.
But it isn't exactly clear what happened in Jacquez's final moments.
Jacquez called Alcon derogatory names before he was shot, according to witnesses Capshaw said were prepared to testify for the state.
"Mr. Jacquez continued to call the defendant names," Capshaw said, "and shots were fired."
Martinez was going to testify that Jacquez was getting ready to slash her with a machete when he was killed, Morrow said.
"If (Alcon) doesn't pull the trigger, Sarah's probably dead," Morrow said.
Morrow said Alcon signed the plea agreement because the state had strong evidence against him on all the charges he was facing, except the murder charge. If convicted of drug trafficking, he would have faced up to nine years in prison for that charge alone.
"After (the shooting, Alcon) did some things of questionable legal nature and he definitely sold drugs," Morrow said.
Alcon's drug charges stemmed from a case prior to the shooting when he was arrested for selling methamphetamine.
After the shooting, investigators said Alcon and other suspects allegedly destroyed evidence.
Jacquez's body was dumped. Martinez's car was taken apart, burned and buried on a 24-acre property near Aztec, along with the clothes Jacquez and the suspects were wearing, according to the San Juan County Sheriff's Office.
Martinez and three other suspects are charged with conspiracy and tampering with evidence in connection to the case. Their charges are pending.
Morrow said Jacquez was a dangerous gangster.
"His reputation is notorious and well-known throughout San Juan County for being violent and aggressive," Morrow said.
Jacquez was charged with murder in the death of Carlos Escobar, 31, who was killed in October 2005 during a gun fight near Bloomfield. In June 2008, a jury acquitted him.
"He wasn't just the violent person they made him out to be," said Jennifer Deuel, Jacquez's mother. She said her son is survived by five children, four brothers and two sisters.
Deuel said Alcon's self-defense claims lost credibility when he and the other suspects tried to hide evidence after the shooting.
"Why would you do that if you were totally innocent?" she said. "They took him out to the middle of nowhere, stripped him down and threw him out. Nobody deserves to be treated like that."
Ryan Boetel can be reached at firstname.lastname@example.org; 505-564-4644. Follow him on Twitter @rboetel