Yu-Gi-Oh! 5D's episode 72: "French Twist, Part 2"
Dr. LeBlanc is the father of Sherry LeBlanc and husband of Mrs. LeBlanc. Both he and his wife were murdered by the mysterious organization of Iliaster, to acquire the special Z-One card he had designed. He had discovered what Iliaster had been up to using the Infinity device. Clark Smith, the president of Momentum Express Development Organization, was then responsible for allowing he and his wife's murder. In the dub version they are instead kidnapped by Iliaster and sent to a currently unknown secret location, though it's implied that they were also killed in the dub.