O.J.'s sister dies By WENN.com

Incarcerated former NFL star O.J. Simpson is in mourning after learning his sister has died.

Carmelita Durio passed away on Monday in Sacramento, Calif., from complications of diabetes. She was 60.

Simpson was devastated to learn his younger sister had died, and broke down in his prison cell at the Lovelock Detention Center in Nevada, according to RadarOnline.com.

"Since Simpson was sent to prison, Carmelita's health deteriorated," a source tells the website. "He blames his Las Vegas legal woes and prison sentence for his sister's death. He believes sending him to prison broke her heart and she's dead because of it."

The 61-year-old was sentenced to at least 15 years in prison last December after being convicted of orchestrating a sports memorabilia heist at the Palace Station Hotel and Casino in September 2007.

He is reportedly planning to appeal his conviction.