On Monday, it was confirmed that MMA fighter Kimbo Slice had died at the age of 42. According to recent reports, he may have died of heart failure.

News about the cause of death of Slice, whose real name is Kevin Ferguson, was reported by the South Florida Sun Sentinel. The news site, which cited a medical report by the Northwest Medical Center, noted that he was that he needed a transplant soon after he was admitted to the hospital on June 3.

According to the report, Ferguson experienced shortness of breath and severe abdominal pains. After being diagnosed with heart failure, he was placed in intensive care and was about to be transported to Cleveland to be included in the donors list. However, this never happened due to his immediate death.

News about his death came as a surprise to the members of the MMA community, who knew Ferguson as a charismatic fighter who rose to the rank of professional athlete after becoming an Internet sensation through bare-knuckle street fights.

But aside from MMA fans, family and close friends of Ferguson were also shocked with what had happened.

"He went to Germany around March and got really sick while he was there," Slice's childhood friend and manager Mike Imber told ESPN. "I don't know what he thought it was, but he just felt sick. On Friday, he had bad chest pains and went to the hospital. I went and visited him on Friday and he seemed OK. I didn't feel like I was going to lose my friend in two days, by any means. He seemed concerned, but he seemed all right."

"I talked to him that Saturday and Sunday, and he was still in the hospital," he added. "I said, 'something's not right.' On Monday, his wife called and told me he had stopped breathing."

Slice, who had a contract with Bellator MMA, was scheduled to take on James Thomspon at the upcoming Bellator 158 event on July 16. However, even before he was hospitalized, his coach Mike Brown said that Ferguson was already considering withdrawing from the match due to certain health concerns.