Authorities say the boy, a goalkeeper, was upset with Portillo after the official penalized the teen with a yellow card for rough play. The teen allegedly struck Portillo in the side of the head as the referee recorded the infraction in his official's notebook.
Unified police investigators turned the case over to prosecutors on Monday, Salt Lake County District Attorney Sim Gill said.
Prosecutors have monitored the case since the incident occurred and are discussing what criminal charges might be appropriate, given the accused's age and Portillo's death, Gill said.
It was not immediately clear how soon charges might be filed.
On Sunday, Portillo's family said they want authorities to hold the teen accountable for his actions but aren't seeking any specific punishment.
"He was old enough to do what he did, then he's responsible to pay for it," Portillo's eldest daughter, Johana Portillo-Lopez, said during a family candlelight vigil."I don't really care what happens to him because whatever he gets, it won't bring my dad back. I just don't want him to do it to another family."
Funeral services for Portillo are set for 5 p.m. Wednesday at Our Lady of Guadalupe Catholic Church, 715 W. 300 North, in Salt Lake City.
A native of Guadalajara, Mexico, who has lived in the U.S. for 17 years, Portillo's body will be returned to Mexico for burial, which was his last wish, his daughter said.
The results of a state medical examiner's autopsy were provided to the family on Monday, Portillo-Lopez said.
"But I can't speak about that until after the prosecutors decide what they are going to do," she said. "All I want right now is prayers."
Portillo's story has gleaned attention from the news media and the soccer community across the globe and brought an outpouring of support and condolences to his family.
"Believe me, he would be surprised by all of this," Portillo-Lopez said. "He's seeing us from up there, and I know he's happy."
Meanwhile, others from the independent, mostly Latino soccer league are hoping that the club won't be unfairly vilified for the tragic event.
League director Mario Vazquez has not responded to multiple requests for comment, but other league participants are speaking out.
Heather Romualdo has played in the league for three years and said the Portillo incident was "uncalled for" and not representative of the league overall.
Romualdo, her husband and her children all play on the league youth and adult teams. Her husband also is a referee, she said.
Based on her experience playing and watching other games, Romualdo said she had never seen a player assault a referee before. Emotions do run high, she said. Sometimes players will brawl among themselves or will argue with game officials, but that kind of behavior is prevalent in other organizations' soccer events, she said.
"I'm not at all surprised that someone threw a punch at a soccer game," said Romualdo, a pediatric exercise physiologist at Primary Children's Medical Center.
Romualdo said she didn't know Portillo or the player who allegedly struck him well, but the entire league has been affected by the event. On Friday and Saturday, before word had spread about Portillo's death, the mood at the games was "subdued," she said.
"I feel terrible for Ricardo's family and for [the player's] family," she said.
Tribune reporters Janelle Stecklein and Jennifer Dobner contributed to this story.
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