(Reuters) – The sister of fraudster Bernie Madoff, who was convicted of masterminding the largest known Ponzi scheme in history, and her husband died last week from an apparent murder-suicide, authorities said on Sunday. Madoff’s sister, Sondra Wiener, 87, and her husband Marvin were found with gunshot wounds on Thursday in Boynton Beach, Florida, according to a statement from the Palm Beach Sheriff’s Office. “After further investigation it appears to be a murder/suicide,” the office said. The medical examiner will determine the cause of death. Madoff died at age 82 last year in federal prison…