Prosecutors say Dotson was gunned down in 2004 to silence the 23-year-old because she had witnessed Ruiz's abduction.
Before he was sentenced Tuesday, Negrete told the judge the victims were gang members who "chose that lifestyle."
The judge called Negrete a coward who had "others to do your dirty work."
The 26-year-old will be eligible for parole after he serves nearly 81 years in prison.
