Kurtz

Feldwebel Kurz was a German officer at Colditz Castle. He was in direct contact with the majority of the prisoners there. He was vicious, delighting in harm to the prisoners, especially ones who had tried to escape. When Ace and the Seventh Doctor arrived there by accident in October 1944, he took a particular interest in her and the contraptions. He dismantled a CD Walkman. At one point, he tried to rape her.

Dr. Elizabeth Klein used him as a lapdog, when she sought the time travellers, mostly threatening to shoot Ace if the Doctor didn't comply with her demands. When the Doctor finally opened his TARDIS to her, the Doctor dematerialised it with the doors open. Kurtz was between the outside world and the interior dimensions of the TARDIS, ripping him apart. His death appalled Ace. She started wanting to be called by her birth name, Dorothy McShane. (AUDIO: Colditz) She later described his death as one of the worst things that she had ever seen. (AUDIO: The Rapture)

In Klein's timeline, Klein was successful in his attempt to kill Ace. (AUDIO: Colditz, AUDIO: Klein's Story)