Lou Pearlman, the founder of boybands Backstreet Boys and *NSync, died from a heart infection, a post-mortem examination has found.
The 62-year-old died in a prison in South Florida on Friday, where he was serving a 25-year sentence for a massive Ponzi scheme.
A report by the Miami-Dade Medical Examiner found Lou contracted the fatal infection of the heart's inner lining after getting a heart valve replaced.
The report said Lou had suffered from a condition in which the heart valve has trouble opening fully.
Lou was convicted of fraud in 2008 after a $300 million Ponzi scheme through his Trans Continental companies was uncovered in 2006.
Hundreds of lawsuits were filed in the music mogul's case, including one by the Backstreet Boys.
Tributes were paid to Lou following his death after he achieved international success with the Backstreet Boys and *NSync, the pop group which launched the career of Justin Timberlake.
*NSync singer Lance Bass wrote on Twitter: "He might not have been a stand up businessman, but I wouldn't be doing what I love today without his influence. RIP Lou."
Aaron Carter, the singer and younger brother of Backstreet Boys star Nick, said: "#LouPearlman my old manager died in prison... Rip Lou not the best business guy really at all but he did discover me karma is real."