Federal prosecutors announced Friday they will seek the death penalty for a former University of Illinois graduate student accused of kidnapping, torturing and killing a visiting scholar from China in June. 
 
 In making the announcement, prosecutors alleged for the first time that Brendt Christensen “choked and sexually assaulted” another victim in 2013 in central Illinois. He also has claimed “additional victims” and expressed a “desire to be known as a killer,” according to prosecutors. 
 
 Christensen, 28, who is being held without bond, had tentatively been set to go to trial Feb. 27 in federal court in Urbana on a charge of kidnapping resulting in a death stemming from the disappearance of 26-year-old Yingying Zhang, whose body has not been found. 
 
 The decision to seek the death penalty — which required the approval of U.S. Attorney General Jeff Sessions — means that the trial will likely be delayed for months. 
 
 The death penalty was abolished in Illinois state court in 2011 after years of allegations of deep flaws in the state’s justice system. In certain cases, though, it remains a tool for federal prosecutors, but its use in federal courts is still rare. It also can take years for an execution to actually be carried out. 
 
 The last person to be sentenced to death in a federal courtroom in Illinois was Dr. Ronald Mikos, who was convicted in 2005 in Chicago of murdering a former patient to keep her from testifying against him in a Medicare fraud trial. 
 
 Mikos, 69, whose appeal to the U.S. Supreme Court was denied nearly a decade ago, is still awaiting execution in federal prison in Terre Haute, Ind., federal records show. 
 
 The announcement in Christensen’s case marks at least the third time in recent weeks that Sessions has opted to push for the death penalty. Earlier this month, it was revealed prosecutors would seek the death penalty against Billy Arnold, an alleged gang member accused of killing two rivals in Michigan. In December, Sessions greenlighted pursuit of the death penalty against Jarvis Wayne Madison, a Florida man who allegedly kidnapped and killed his estranged wife. 
 
 In their five-page motion Friday, prosecutors said the death penalty was warranted because Christensen “is likely to commit criminal acts of violence in the future that would constitute a continuing and serious threat to the lives and safety of others.” 
 
 No details of the alleged 2013 sexual assault by Christensen were provided other than the initials of the victim, “M.D.” The alleged assault occurred the year Christensen was admitted to the university’s highly competitive physics graduate program. 
 
 Four years later, Zhang's sudden disappearance rattled the U. of I. campus and sent shock waves throughout China. 
 
 Zhang, who began her research appointment last April, tried unsuccessfully to flag down a bus before walking to another stop the afternoon of June 9. Shortly after, federal authorities allege, Christensen approached Zhang in his black Saturn Astra sedan and lured her inside. 
 
 Surveillance video from a nearby parking garage captured the exchange in which Zhang could be seen speaking to the driver for several moments before getting into the front passenger seat. 
 
 The investigation focused on Christensen after police concluded his Saturn was the car seen in the video. He initially told the FBI he was home all day playing video games on the day Zhang disappeared. 
 
 Yingying Zhang, 26, a visiting scholar at the University of Illinois, has been missing since June 9, 2017. Authorities say she is presumed dead. Brendt Christensen, 28, has been charged with kidnapping Zhang. 
 
 When he was questioned a second time, Christensen changed his story, telling agents he got the date mixed up, according to court records. He said he was driving on campus, came across an Asian woman looking distressed and offered her a ride because she said she was late to an appointment, authorities said. Christensen said the woman panicked after he made a wrong turn, and he let her out of his car a few blocks from where they met, prosecutors said. 
 
 Meanwhile, police searched Christensen’s car and determined that the area where Zhang would have been sitting had been cleaned in a way to conceal evidence, according to prosecutors. Police also searched his phone and found visits to a sadomasochism fetish website with discussion threads on kidnapping fantasies, prosecutors said. 
 
 On June 29, Christensen attended a campus rally for Zhang with a girlfriend, who unbeknownst to him was wearing an FBI wire. He was captured on audio recordings describing his "ideal victim" as he pointed out people in the crowd, prosecutors have previously said. 
 
 Other recordings made that day captured Christensen admitting to having kidnapped Zhang and describing how she fought back as he held her against her will, according to prosecutors. 
 
 Earlier this week, a defense filing revealed that a few hours before Zhang’s kidnapping, a female U. of I. graduate student reported to police that a man wearing aviator sunglasses had pulled up to her in a black sedan and flashed a badge. She refused to get in the car and he drove off. 
 
 A few days later, the woman picked out Christensen’s photo from among six shown her by the FBI, but Christensen’s lawyers are seeking to block the testimony, saying she couldn’t be certain because of the sunglasses. 
 
 She did say that of the six photos, Christensen "shared the most characteristics" of the man because of his "short, dark hair and tan face," the filing said. 
 
 jmeisner@chicagotribune.com 
 
 Twitter @jmetr22b 
 
 RELATED: Earlier abduction attempt reported on day Chinese scholar went missing at U. of I. » 
 
 Parents of missing Chinese scholar: 'I don't know how to spend the rest of my life without my daughter' » 
 
 At vigil for missing Chinese scholar, suspect talked about 'ideal victim,' prosecutor says » ||||| Former University of Illinois graduate student Brendt Christensen could be eligible for the death penalty if convicted on new charges filed Tuesday alleging he kidnapped and killed a visiting scholar from China in June. 
 
 Christensen, 28, of Champaign, was charged in a superseding indictment with one count of kidnapping resulting in a death stemming from the disappearance of 26-year-old Yingying Zhang, whose body has not been found. 
 
 The federal grand jury returned the four-page indictment with the special finding that Christensen committed the offense “in an especially heinous, cruel or depraved manner, in that it involved torture or serious physical abuse to the victim,” and that the crime occurred after “substantial planning and premeditation.” 
 
 The indictment also charged Christensen with two new counts of making false statements to FBI agents. 
 
 Christensen could face the death penalty if convicted on the new kidnapping charge, although the decision whether to seek it will be made at a later date by U.S. Attorney General Jeff Sessions, according to a news release from the U.S. attorney’s office in Urbana. If the death penalty is not sought, a conviction on the kidnapping count would call for mandatory life without parole. 
 
 Christensen, who is being held without bond, is tentatively set to go to trial Feb. 27 before U.S. District Court Judge Colin Bruce. Reached by telephone Tuesday, his lawyer, Robert Tucker, said he had not seen the superseding indictment and had no comment. 
 
 The new charges were the latest twist to a case that rattled the University of Illinois campus and sent shock waves throughout China. 
 
 Prosecutors allege Zhang, who began her research appointment in April was on her way to sign a lease at an apartment building the afternoon of June 9 and unsuccessfully tried to flag down a bus before walking to another stop. Shortly after, federal authorities allege that Christensen approached Zhang in his car and lured her inside. 
 
 Surveillance video from a nearby parking garage captured the exchange in which Zhang could be seen speaking to the driver for several moments before getting into the front passenger seat. One of Zhang's professors reported her missing by that evening, after several calls and texts went unanswered. 
 
 The investigation homed in on Christensen after police concluded his Saturn Astra was the car seen in the footage. He initially told the FBI he was home all day playing video games on the day Zhang disappeared. When he was questioned a second time three days later, Christensen changed his story, telling agents he was driving on campus, came across an Asian woman looking distressed and offered her a ride because she said she was late to an appointment. 
 
 Christensen said the woman panicked after he made a wrong turn, and he let her out of his car a few blocks from where they met. Meanwhile, police also searched his car and determined that the area where Zhang would have been sitting had been cleaned in a way to conceal evidence, FBI agents alleged in court documents. 
 
 Police also searched his phone and found visits to a sadomasochism fetish website with discussion threads on kidnapping fantasies. 
 
 The FBI also conducted audio surveillance on Christensen for several days, including when he attended a campus walk and vigil in Zhang's honor on June 29. There, Christensen was caught on tape pointing out people in the crowd and describing his "ideal victim." 
 
 Other surveillance tapes recorded Christensen allegedly admitting to having kidnapped Zhang, and describing how she fought back as he held her against her will, prosecutors said. 
 
 Police and prosecutors have not revealed the source of the recordings. 
 
 jmeisner@chicagotribune.com 
 
 Twitter @jmetr22b
– University of Illinois graduate student Yingying Zhang disappeared in June. The Chinese woman's body has not been found, but federal prosecutors believe that Brendt Christensen is responsible for her murder—and they announced Friday that, with Attorney General Jeff Sessions' blessing, they will pursue the death penalty in their case against him. The Chicago Tribune looks at just how rare a thing such a conviction and sentence would be. Illinois did away with the death penalty in 2011, and its use in federal court is far from commonplace. More on the case, the move, and the growing allegations against Christensen: The Tribune reports the last instance of the federal sentence being imposed in Illinois court was in 2005, when Dr. Ronald Mikos was found guilty of murdering a one-time patient who was cooperating in a Medicare fraud trial against him. The Supreme Court declined to hear his appeal in 2009, the AP reported at the time, but he still awaits execution.