Sitting on a bench at a vigil for missing Chinese scholar Zhang Yingying in 2017, Brendt Christensen grabbed his girlfriend Terra Bullis’ phone and pulled up the note function. One at a time, he typed four lines then deleted each one after showing them to her. “It was me.” “She was number 13.” “She is gone.” “Forever.” When he saw the crowd gathering for the vigil, he told Bullis “they’re here for me”. Christensen was smiling and appeared happy at the sombre vigil, Bullis said. She wore a wire for the FBI to record nine conversations with Christensen, including one the same evening in which Christensen told her in graphic detail how he killed Zhang. Christensen was “excited” and “boastful” and claimed Zhang was his 13th victim, Bullis testified on Thursday at her ex-boyfriend’s trial for the kidnapping and murder of Zhang, a scholar at the University of Illinois. Vanished Chinese scholar Zhang Yingying’s parents arrive in US for trial of her alleged killer, Brendt Christensen “They have the bat I hit her in the head with,” Christensen told Bullis, referring to the FBI, adding that he first tried to choke Zhang to death. “I couldn’t believe she was still alive.” He said he carried her to his bathtub. “I got the bat and hit her on the head as hard as I could and it broke her head open,” Christensen said. Then he stabbed her in the neck and “chopped her head off”, he said, laughing. The conversation was on June 29, 2017, about three weeks after the June 9 disappearance of Zhang, as authorities were zeroing in on Christensen as a suspect. Bullis conveyed interest in an effort to keep the conversation going, but was “devastated”, she said. “Do you think you might be the next successful serial killer?” Bullis asked Christensen. “I already am,” he replied on the recording. Despite his boasts, FBI agents have testified that no evidence has been found to link any other victims to Christensen. Defence lawyers have admitted Christensen killed Zhang, but insisted he wasn’t being truthful when he said he killed other people. Christensen is facing the death penalty , which was abolished in Illinois state courts, but is still an avenue federal prosecutors can pursue. Zhang was last seen on June 9, 2017, getting into a black Saturn Astra near the Champaign-Urbana campus at the University of Illinois. Thursday was Bullis’ second day testifying. Christensen was drinking alcohol from a water bottle at the vigil, but she said he did not appear to be drunk. In one recording, Bullis said did not think he would harm her or his wife, Michelle, with whom he was in an open relationship. Christensen told Bullis she was “safe”. Bullis said she would not be safe if she told anyone about their conversation. “That’s true,” Christensen said. Christensen, 29, was arrested the day after that conversation. He called Bullis several times after his arrest, she said. Bullis became emotional several times during her many hours of testimony on Thursday, at times wiping her eyes. She left her job after Zhang’s disappearance, in part because photos were released of her with Christensen so she could not work in a public setting, she said. She has received up to US$8,000 from the bureau for mental health treatment, she said on Thursday. In a July 2, 2017 phone call between Christensen, who was in jail, and his wife, he asked her to reach out to Bullis. “Please text her or call her and tell her not to say anything to anyone except our lawyers,” Christensen said. “Tell her I’m innocent and everything is going to be OK.” US man Brendt Christensen, accused of killing visiting Chinese scholar Zhang Yingying, abandons mental health defence In his cross-examination of Bullis, assistant federal defender Robert Tucker highlighted Christensen’s “severe” issues with alcohol, emotional and psychiatric issues she was dealing with and her alternative sex life with Christensen. Bullis said she was struggling at the time, taking medication and suffering from PTSD related to something else. Tucker suggested that during the conversations, Bullis was asking Christensen leading questions to get him to implicate himself. She said she drank alcohol from the water bottle Christensen took to the vigil because she thought if she did not that he might not keep talking to her. “You wanted to drink with him and keep him drinking, didn’t you?” Tucker said. “That’s incorrect,” Bullis said. Bullis said she contacted Christensen on the dating website OKCupid in April 2017 and introduced him to “kink” and BDSM (bondage and discipline, dominance and submission, and sadism and masochism). Special Agent Greg Catey presented analysis of Zhang and Christensen’s mobile phones. Zhang’s phone did not communicate with an AT&T tower after 2:28pm on June 9, 2017, he said. A camera recorded her getting into the Astra less than 30 minutes earlier. Zhang’s phone has not been found. Testimonies continue on Friday and closing statements are expected on Monday.