The man said police are the main suspect in the kidnapping and murder of Andrea Bharatt.
Police Commissioner Gary Griffith confirmed to Guardian Media that the 37-year-old Joel died while being treated at Mount Hope Hospital.
Other senior police sources told Guardian Media that he died around 2.40pm.
Belcon sources said it was the man who drove the Nissan Versa in which Bharatt was abducted on January 29.
Belcon, a well-known sex offender, was detained two days later along with several other persons for questioning about her disappearance.
He made an attempt last Sunday to escape from police custody at Jacob Settlement in Sangre Grande.
Belcon, aka Devon Charles, believes investigators are responsible for the disappearance of several women, including one woman who went missing 13 years ago.