Raul Avalos, 26, was arrested March 18 and charged with attempted murder and 16 other felonies, including assault, aggravated battery, child abuse and battery on a peace officer.
The San Juan County Sheriff's Office said the incident occurred at the end of an all-night St. Patrick's Day party. Garrett was shot twice in the chest while sitting on a couch next to his sister, according to court documents. His wounds included heart damage.
He survived the shots initially but never fully recovered.
Garrett's relatives said his life after the shooting was "hell."
"He had night terrors, cold sweats and was in and out of the hospital," said Amanda King, a close family friend who Garrett called "Auntie."
Garrett's sister, Chantara, was shot in the leg at the party. A bullet grazed another man's wallet and he was uninjured, according to court documents.
At least seven people, including a 15-year-old girl, witnessed the shooting and identified Avalos as the shooter, according to court documents.
Witnesses said Garrett and Avalos exchanged "looks" prior to the shooting, according to court documents.
Eric Morrow, Avalos' attorney, said the witnesses won't appear credible in front of a jury.
"This case has more problems than a porcupine has needles," he said. "The state is upping the charges because they can and they are trying to push my client into pleading to something else."
Morrow said he'll comb through Garrett's medical reports to see if there is another explanation for his death.
A document filed in September said Garrett had to be readmitted into the hospital because of heart problems and that he was suffering from severe psychological problems.
Assistant District Attorney Ken Stalter said the office hasn't received a copy of Garrett's autopsy report but Garrett's doctors can prove he died as a result of the shooting.
Garrett, of Aztec, died on Nov. 3, two days after his 20th birthday. He was at a Denver hospital waiting for a heart transplant, King said.
Garrett was healthy and athletic prior to the shooting, she said.
"He was a kickboxer," King said. "He had no health problems at all."
He had a three-month-old son and a stepdaughter. His parents are Bobbie Jean Carter and Gary Floyd White.
Garrett was at a party at the Vargas home at 603 Taos Ave. when he was shot.
The home has a long history with the sheriff's office, who respond to the house more than once a month on average, according to sheriff's office statistics.
The house was the scene of two homicides in the last five years.
In March 2007, Kailie Sitta, a 15-year-old Farmington girl, was shot and killed at the end of a party. Her case remains unsolved.
Both of the homicides occurred at the end of St. Patrick's Day parties hosted by the Vargas brothers, who live at the address.
Danny Vargas, 24, is currently incarcerated for three alleged probation violations that stem from a misdemeanor conviction.
Adam Vargas, 23, is scheduled to be arraigned in district court next week on a charge of felony aggravated battery on a health care worker.
Police said Adam Vargas bit a paramedic who was treating him after he was in a fight, according to court documents.