Court documents submitted by the Bernalillo County district attorney last week said the vomit and an argument over a cleanup fee led to the shooting, the Albuquerque Journal reported .
Police say driver Clayton Benedict fatally shot passenger James Porter, 27, after stopping along a highway in Albuquerque on March 17. Benedict has not been charged and has declined to comment.
A charging decision may come in the next few weeks, district attorney spokesman Michael Patrick said.
"Prosecutors are currently going over hundreds of documents and videos," Patrick said.
The friend, Jonathan Reyes, later told police the two had been at the bar since 2 p.m. and although he typically doesn't drink, he had six or seven drinks that day.
Benedict — who had been driving for Uber for a year and a half — told detectives they were traveling south on Interstate 25 when Reyes threw up in the backseat.
"At this point, the other passenger and Clayton start to go back and forth about a potential 'clean-up fee,'" the detective wrote in the affidavit. "James is the male arguing/pleading with Clayton not to charge him for a 'clean-up fee.'"
That's when Benedict said he pulled over and asked the men to get out of the car. He said he ended the ride and gave Porter a review of "one star." He said Porter slammed the door and the two argued outside the car.
Benedict said Porter was yelling and moved toward the open driver's side door, threatening to run Benedict over with his own car. Benedict said he fired "an unknown amount of rounds" toward Porter.
Porter's family sued Uber and Benedict last month. The San Francisco-based Uber told the newspaper in a statement that Benedict no longer has access to the Uber app as a driver.
Last year, an Uber driver in Denver was charged with murder in the fatal shooting of a passenger on a Colorado highway. Police have said driver Michael Hancock, 29, shot and killed Hyun Kim, 45, following an altercation in the car. Hancock's family has said he only shot in self-defense.