PORTLAND, Ore. — Prosecutors say a FedEx driver was justified in punching a Portland, Oregon, man after he yelled racial slurs and tried to hit the driver first. Joseph Magnuson died following the September encounter with driver Timothy Warren, The Oregonian/OregonLive reported.

The Multnomah County District Attorney's Office announced Monday that there's no indication Warren intended to kill Magnuson.

A county medical examiner determined Magnuson was in "extremely poor health" prior to the encounter, and his fall after the punch to the head aggravated pre-existing conditions.

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Witnesses told authorities Magnuson was yelling "very aggressively" for Warren to slow down, Senior Deputy District Attorney Adam Gibbs wrote in a memo declining prosecution. Three witnesses, however, said Warren was driving slowly — 20 miles per hour or less — on the narrow road by a playground, reports Oregon Live. Warren stopped the truck and tried speaking to Magnuson.

If Warren kept driving, Magnuson might still be alive, but "the decision by Mr. Warren, who is black, to not let the racist vitriol to which he was being subjected go unanswered is not of legal significance," Gibbs wrote.

Both men started yelling at each other, and Magnuson threw a drink at Warren. Warren hit Magnuson once after he threw a punch, according to the memo. Magnuson dropped to the ground unconscious.

"Oregon law contains no 'duty to retreat' and Mr. Warren was within his right to exit his vehicle and verbally challenge the manner in which Mr. Magnuson was addressing him," the memo said. "Mr. Magnuson was the initial verbal aggressor; Mr. Warren responded in kind. Mr. Magnuson then escalated and became the initial physical aggressor; Mr. Warren again responded in kind."

Magnuson's toxicology results weren't immediately available, reports Oregon Live, but Gibbs wrote the findings "are not of significance to the legal analysis."

Magnuson's toxicology results weren't available as of Monday, Gibbs wrote, but the findings "are not of significance to the legal analysis."