The impact to the chest likely induced a fatal arrhythmia, according to his doctors, who are awaiting the results of an autopsy.
Doherty said he found no fluid around the boy's heart to suggest atropic cardiomyopathy, a genetic condition (enlarged heart) that is most often associated with the deaths of young athletes. There were also no injuries to the chest.
Fatal arrhythmias occur when an impact to the chest causes an exaggeration of the normal electrical activity of the heart during a "susceptible" period in heart rhythm, according to Doherty, who said an external defibrillator at the scene could have saved the boy's life.
"This is a good example where for children's or young adults' athletics, it's a good idea to have it around. "If [Maurice] had access to it -- any lay person can use it -- it may have saved his life."
There are more than 250,000 sudden cardiac deaths per year and most are thought to be from ventricular fibrillation.
The term "arrhythmia" refers to any change from the normal sequence of electrical impulses. The electrical impulses may happen too fast, too slowly, or erratically -- causing the heart to beat too fast, too slowly, or erratically.
When the heart doesn't beat properly, it can't pump blood effectively. Then the lungs, brain and all other organs can't work properly and may shut down or be damaged.
According to heart rhythm specialist Dr. David E. Haines, who did not treat Maurice, a blow to the chest used to be used routinely in CPR training.
"The idea behind a good thump to the chest is that it acts like a stimulus, and we used to think the shock could potentially terminate potentially abnormal rhythms," said Haines, chairman of the cardiology department at William Beaumont Hospital in Royal Oak, Mich.
"But it can work the opposite way as well," Haines told ABCNews.com. "A thump to the chest in the wrong timing relative to the cardiac cycle can initiate a life-threatening arrhythmia."
These fatal arrhythmias happen in sports like karate and baseball, where there is inadequate chest protection, according to Haines, who said a move was afoot to compel baseball manufacturers to "beef up" the design of uniforms and equipment.
"Any blow to the chest at exactly poor times can kill an otherwise completely healthy person," he said. "It's uncommon, but it's out there."
Meanwhile, Maurice's family is mourning the death of the young teen.
"I believe they took him for a reason," said Booker Hatcher. "He went through a lot of stuff with his mother and father not being there. But he was peaceful and I am glad he touched kids' lives at his school. We talked to his teammates and everybody loved him."