He was among five teenage gang members who were charged with plotting the carjacking of Vincente Huerta in the summer of 2007.
During the carjacking, Huerta was shot and killed.
In 2010, following a cold case murder tip, police arrested Augustine Alvarez and four others and charged them with capital murder.
Charges against Alvarez were later reduced to aggravated robbery when it was determined that another teen, Aaron Alaniz, did the shooting.
“The crime was reduced because of what we believed the evidence would show about his culpability,” said prosecutor Mary Green, following Alvarez’s sentencing on Thursday.
Judge Angus McGinty sentenced Alvarez to 20 years in prison on the robbery charge.
When he was charged in connection with Huerta's murder, Alvarez was in prison following his conviction in an assault case that occurred after Huerta was killed.
“A reasonable person, having been involved in a terrible crime, might make a conscious effort to stay out of trouble,” Green told the judge prior to sentencing. “But this young man did not.”
Alaniz was tried for Huerta’s murder in November 2012 and is serving a life-sentence.
Alvarez will have to serve half of his 20-year sentence before he is eligible for parole.