The 28-year-old was arrested after police discovered the body of his wife Jennifer Viera in a hotel room in his native Venezuela on Sunday morning. Valero is said to have alerted security himself after confessing to stabbing her three times.
He was detained by police and was expected to be charged with murder, but was found hanged by a fellow inmate yesterday morning having tied his own clothes to a cell bar.
Unbeaten Valero was on the verge of breaking into the big time after 27 consecutive stoppage victories, 19 of which came in the first round.
He successfully defended his WBC lightweight title against Antonio DeMarco two months ago but was later suspended after expressing a desire to fight at a higher weight.
Valero had also became known as the bad boy of boxing after several run-ins with the police.
Just last month he was charged with harassing his wife and threatening medical staff, who treated her for a series of injuries including a punctured lung and broken ribs.
Valero escaped punishment after his wife told police she had fallen down a flight of stairs, yet he was subsequently sent for six months of drug and alcohol rehabilitation.
In 2001, Valero was involved in a motorcycle accident that resulted in him suffering a brain injury, which prevented him from being licensed to fight in many US states.
Dubbed “Inca”, alluding to an Indian warrior, Valero had a huge image of president Hugo Chavez tattooed on his chest along with the country’s yellow, blue and red flag.