Matthew and Ryan Kent were twins and victims of The Gravedigger.
They were kidnapped in 2001 and were the third victims of the Gravedigger. The FBI advised their father to not pay the ransom and he did not. Their father, James Kent blames himself and the FBI for their deaths for this reason. Mr. Kent told Bones and Booth that his sons were good kids. It was revealed that the Gravedigger only meant to kidnap one boy, but the other saw her and attempted to attack her, so she stunned them and took them both. Because of this, they only had twelve hours of air each, instead of the usual twenty-four. It would not have mattered if the ransom was paid as they still would have died.
It is then revealed that Ryan Kent stabbed himself and bled out to give his brother more air. After Heather Taffet was found to be the Gravedigger, her other cases were thrown out, and she was then tried and convicted of being the Gravedigger and maliciously murdering a young boy. Later, when she is walking into the courthouse for a last appeal, she is shot through the head and killed by as it's uncovered, Jacob Broadsky, who approached their father, James Kent, for two million dollars to kill her. James Kent later confessed and was taken into custody. Currently, he is still in incarceration for paying Broadsky to kill the Gravedigger.