Tupac Shakur was in Rikers Island on sexual assault charges when L.A. rap entrepreneur Suge Knight offered to pay his $3 million bail on the condition he sign with Knight’s Death Row Records.

While incarcerated at Rikers Island, Tupac penned a heartfelt message to Madonna, explaining the reasons behind their breakup. The letter, dated January 15, 1995 not only revealed his affection ...