A 50-year-old man whom authorities say killed another man with a single punch at Portland International Raceway this past summer has himself died.

Michael Eugene Taylor had been headed to trial next month to contest accusations of second-degree manslaughter and assault of motocross racing fan Anthony Mancuso, 61. But Taylor died days before Christmas.

It's unclear what caused his death. He had a list of health problems, including diabetes, blood clots, high blood pressure, scoliosis and Celiac Disease, according to court reports.

Taylor's criminal defense attorney, David Shannon, declined comment on Wednesday. He said Taylor's family has requested privacy.

According to authorities, Taylor and Mancuso's adult sons had competed in a motocross race on July 9, 2015. The sons had gotten into some sort of dispute during the competition, and tensions spilled into the parking lot afterward. According to some witnesses, Mancuso tried to intervene and that's when Taylor -- who appeared to be the aggressor -- punched Mancuso even though Mancuso had done nothing wrong, the witnesses said.

Mancuso's head struck the ground hard, and he died the next day.

Taylor's son and Taylor told a different story. Taylor reportedly told police: "Yeah, I hit him. It was self-defense. He elbowed me in the face and his son attacked me. I had no choice."

A conviction for second-degree manslaughter would have meant a minimum prison sentence of six years and three months for Taylor.

Taylor was released from jail pending trial after he posted bail Sept. 14, the day a Multnomah County Circuit judge lowered his bail from $500,000 to $20,000. Taylor was required to post 10 percent of that.

During Taylor's bail hearing, he told Judge Angel Lopez that had about $100 in his bank account, and that he's been unemployed since October 2014 because of his health problems. According to court records, he told authorities that he had been a machinist for 10 years, had been living off of 401(k) savings until that dried up and had been planning to start an automotive business.

-- Aimee Green

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