Vincent called Draper police for backup, and two officers arrived moments later.
Also at the scene was a West Valley City police sergeant, who lives in the neighborhood and was returning home from a graveyard shift when she happened upon the scene.
The officers were about to arrest Nielson on suspicion of a narcotics violation when he broke free and produced a butcher knife while still inside in the SUV.
"When the struggle ensues inside the cab of the [SUV], there's [four] officers on the driver's side attempting to take the gentleman back out of the car," Eining said. "And that's when the knife is produced."
Eining said a Draper officer was between Vincent and Nielson when the knife came out. Vincent spoke aloud that there was a knife, then fired multiple shots, which killed Nielson.
Vincent suffered minor lacerations to his hands, but Eining said at an afternoon news conference that he did not know if Vincent was injured by the knife — described as a kitchen or butcher knife with an 8-inch blade — or from the altercation in general.
Though the investigation into the shooting is ongoing, Eining's personal opinion is that the officers "did everything they could do in this situation" and acted appropriately.
"We have an officer that recognized a threat and within seconds, he had to identify the threat, and the danger that that person posed to the other officers involved, and had to act on that threat," Eining said. "And again, this is an incident that involved deadly force by a suspect, and was met by deadly force by an officer."
Eining said they found narcotics, but he did not identify what kind.
Police provided no further information on Nielson, whose body remained at the incident scene at least into late Wednesday afternoon. But court records show that when he died, Nielson was facing misdemeanor charges of criminal trespass and assault. In court documents, Sandy police wrote that on Dec. 6, Nielson went into the apartment of his wife's friend, where his wife was sleeping, ripped the sheets off her and pinched her. His wife also had a protective order against him.
In 2004, Nielson faced dozens of charges; in cases filed in Salt Lake, Davis, Utah and Millard counties, he pleaded guilty to at least 20 felony and misdemeanor counts, including burglary, forgery, identity fraud, theft, criminal mischief, disorderly conduct, drug charges and traffic violations, and he agreed to enter a drug treatment center.
In 2010 and 2011, Nielson successfully petitioned the judges to reduce his felony convictions to misdemeanors. That prompted objections from a former friend and co-worker, who wrote to the judges in 2013, claiming that Nielson had threatened him and his family, and would be able to make good on violent threats because he "trains as a professional [mixed martial arts] fighter."
"Jeffrey R. Nielson has a long history of violence, drug abuse and financial related crimes," wrote Josh Lindsay. "While I believe that some people can actually rehabilitate and move forward as productive citizens, I am positive this is not the case with Jeffrey R. Nielson. … Giving [Nielson] a fresh start would be an act of fraud to the general public."
In 2010, Danielle Lindsay, Josh's wife, sought a stalking injunction against Nielson, who she said sent a text to her husband, stating: "I don't want to hurt you or your family, josh, but I will!!!"