(CNN) -- A Michigan referee of an adult-league soccer match died Tuesday, two days after being punched in the head by a player, authorities said.
John Bieniewicz, 44, died at Detroit Receiving Hospital from injuries suffered in what police said was an unprovoked attack. The blow left the victim unconscious and not breathing on the field, Livonia Police Chief Curtis Caid said.
After the attack, the player fled the field and waved his middle finger at the crowd.
Bieniewicz was in critical condition when he reached the hospital and was pronounced dead Tuesday morning.
"John Bieniewicz was a man who lived life to the fullest," friends wrote on a website dedicated to his memory. "He had a passion for his family, a passion for the kids at Mott Children's Hospital, and a passion for soccer. John died doing what he loved: Officiating a soccer game."
The Wayne County Medical Examiner's office will determine the cause of death, according to Livonia police.
The alleged attacker, Baseel Abdul-Amir Saad, 36, was charged with assault with intent to do great bodily harm less than murder. He was being held on $500,000 bail, police said. He pleaded not guilty.
The investigation is ongoing and authorities "anticipate the criminal charges to be modified as a result of Mr. Bieniewicz's death," police said.
Defense lawyer Brian Berry expressed his condolences to the family of the referee, but also said all the facts in the case had not come out and that "witness accounts may have been miscategorized."
A hearing was set for July 10.
Bieniewicz is survived by his wife and two sons, age 13 and 9.
On the website, the Bieniewicz's friends remembered him and sought to raise money for his family.
The site said Bieniewicz was a licensed soccer referee at all levels, professional, collegiate, high school and children's leagues, was president of the Metro Detroit Soccer Officials Organization, and sometimes refereed three games on a Saturday.
"He also took a particular interest in all the children he worked with Monday thru Friday at the pediatric dialysis center at Mott, and reveled in their improvement and happiness," the site said.
The site added, "The boys will miss his fatherly guidance and support but they will also miss his financial support, and we are here to help that in a small way. If you were touched by John, or merely share his love of soccer, we ask that in his name you donate to his children's futures."
Last year, a 17-year-old soccer player in Utah pleaded guilty to homicide by assault in the death of referee Ricardo Portillo. A judge ordered the teenager, who was not named publicly, to keep a picture of Portillo in his cell for the remainder of his time in juvenile jail.
The judge recommended a sentence of three years, said Salt Lake County District Attorney Sim Gill. The teen also was ordered to write weekly letters to Portillo's family, telling them what steps he is taking to return to normal life.