The family of Joseph Lee says the boy loved sports and wanted to be a professional baseball player.
Betty Lee, Joseph's mother, struggled while speaking to ABC7 Chicago to find some sign of the tragedy, just hours after her son suddenly collapses and died.
" There was no sign at all. There was no complaint during the week, no complaint that day," she said.
Joseph Lee was a stand-out eighth-grade student at Central Junior High. Saturday morning, his mother reminisced about how her son's personality drove his desire to one day become a professional baseball player and how it made him an all around great kid.
"[ He was a] very mannerable child, avoided confrontations at all times, no fights, just a very pleasant child," Betty Lee said.
The 12-year-old was rushed to the hospital Friday night after he and his friends played a game of pick-up basketball at the local community center. Joseph's best friend, Devonte Williams, says it was as the boy ran down a rebound that he fell to the gym floor and never got up.
"I'm just trying to stay strong and be there for him," Williams said through his tears.
The Cook County Medical Examiner listed Joseph's official cause of death as hypertrophic cardiomyopathy, or death as the result of an enlarged heart.
Lee's family says his death is especially difficult to handle because he never showed any signs of any heart condition, with the exception of a heart murmur as an infant. Relatives add that in the nine years he had been playing Little League baseball, he had to take physicals to qualify, and nothing showed up.
So, as family and friends gathered to support Joseph's parents, big sister and little brother over the weekend, his mother tried to draw on her training as a registered nurse to make her child's death understandable.
"You learn how to cope, I've learned that in my schooling, but when it comes to your own, it's very difficult," Betty Lee said.
Funeral arrangements for Joseph Lee were pending Saturday night.
Grief counselors were expected to be on hand Monday at Joseph's school for his classmates and teachers.