Sebastian Telfair's sister has been arrested by the FBI for allegedly making violent threats to the ex-NBA star's estranged wife ... TMZ Sports has learned.
We broke the story ... Samantha Telfair had gone to police in late April claiming she was getting frightening phone calls from Octavia Telfair, who threatened to "kill my kids and cut my face" all because she testified in Sebastian's NYC gun case.
During Sebastian's trial, Samantha told prosecutors she had personally witnessed the former basketball star in possession of multiple weapons, including the gas-operated submachine gun he was allegedly carrying when he was arrested in June 2017.