Task: Question Generation
Input (English): Passage: After an April 21, 1995, court hearing on the gun charges, but before McVeigh's release, federal agents took him into custody as they continued their investigation into the bombing. Rather than talk to investigators about the bombing, McVeigh demanded an attorney. Having been tipped off by the arrival of police and helicopters that a bombing suspect was inside, a restless crowd began to gather outside the jail. While McVeigh's requests for a bulletproof vest or transport by helicopter were denied, authorities did use a helicopter to transport him from Perry to Oklahoma City.Federal agents obtained a warrant to search the house of McVeigh's father, Bill, after which they broke down the door and wired the house and telephone with listening devices. FBI investigators used the resulting information gained, along with the fake address McVeigh had been using, to begin their search for the Nichols brothers, Terry and James. On April 21, 1995, Terry Nichols learned that he was being hunted, and turned himself in. Investigators discovered incriminating evidence at his home: ammonium nitrate and blasting caps, the electric drill used to drill out the locks at the quarry, books on bomb-making, a copy of Hunter (a 1989 novel by William Luther Pierce, the founder and chairman of the National Alliance, a white nationalist group) and a hand-drawn map of downtown Oklahoma City, on which the Murrah Building and the spot where McVeigh's getaway car was hidden were marked. After a nine-hour interrogation, Terry Nichols was formally held in federal custody until his trial. On April 25, 1995, James Nichols was also arrested, but he was released after 32 days due to lack of evidence. McVeigh's sister Jennifer was accused of illegally mailing bullets to McVeigh, but she was granted immunity in exchange for testifying against him.Ibrahim Ahmad, a Jordanian-American traveling from his home in Oklahoma City to visit family in Jordan on April 19, 1995, was also arrested, amid concern that Middle Eastern terrorists could have been behind the attack. Further investigation cleared Ahmad of any involvement in the bombing.
Output (English): What is the last name of the person Jennifer was granted immunity in exchange for testifying against?