Hello kittythehare, thanks for asking your questions. I know you followed the case closely throughout. Unfortunately, I don't have great answers for these questions. I'll do my best to outline what we knew.
Regarding the amount of blood we recovered - it wasn't much. We could make inferences based on where it was located, but we could not tabulate how much blood was lost from what we recovered. For example, there was spots of Yingying's blood on the mattress. Those amounts were small. The blood from underneath the tack strip and soaked into the floorboard is more telling. That blood had to be a sufficient quantity to drip down the wall, soak under the tack strip and carpet, soak into the wood and carpet, and still be leftover from his extensive cleaning efforts. I think it's a fair inference to say that was quite a bit of blood. The little pool of what was leftover after cleaning was not large - maybe 10" x 4-5" or so. Was it enough to show death just from the amount of blood lost? I'm not certain. That was one of the things I wanted to hire an expert to do, but we ultimately chose not to, as there was a significant risk if the amount of blood was not sufficient to show death. We felt we had enough to prove Yingying's murder without introducing more uncertainty.
Regarding the bathroom - remember, Christensen had a professional cleaning done on the tub. It was unlikely we would recover anything after that cleaning. He missed cleaning under the vanity, however, and the cadaver dog picked up that odor several weeks later. Where did he kill her? It would have been hard to swing a bat in that bathroom, but that's what he claims he did. I don't have any answers on that.
RE: the disposal of her body, that is the mystery, isn't it? The prosecution / investigatory team still believes Christensen disposed of her body in the trash bin, and that her remains are in the landfill somewhere. There is still interest in other locations, notably Allerton Park, but nothing concrete that moves the general belief off the landfill hypothesis. We have no credible evidence to suggest Christensen buried the remains, nor that he burned them. Burning a body would take quite a bit of time and effort. Christensen was lazy. He never went outdoors (beyond to and from class) if he could avoid it. He had no tools to dig a grave and burn a body. It's possible he had them and got rid of them, but that seems to be against his general character.
Regarding trophies / videotaping, that is all possible. His electronic devices were all seized and reviewed, however, and we found no trace of any video involving Yingying. His accessing his *advertiser censored* files after the murder - when Yingying's body was still in his apartment - is beyond disgusting. In all probability, he was masturbating with a dead body partially dismembered in his bathroom. I suppose it is possible he videotaped the murder, hid it in his *advertiser censored* file, and was watching it at that time - and then later deleted it - we just don't know. We did not find any videos of the murder.
We know, from MC and TEB, that Christensen came up with a ridiculous explanation for the disappearance of the giant bag he ordered. He left the house with it after MC had returned, and told MC and TEB it contained a broken cat tree that someone must have stolen from the grounds near TEB's residence (NOTE: the jurors laughed continually about this ridiculous story - they told us after the trial how ridiculous they found it). Christensen later told us the bag contained Yingying's belongings, etc., and that he drove around C-U dumping it in dumpsters. That bag likely also contained the knives and cleaning materials. Remember, the bag had been in a closet in their house, and the agents found baking soda in that area during their search (which, per MC, was not there when she left). It's possible he kept trophies initially, but decided the heat was too much, and ended up dumping them.
I don't believe Yingying was alive long in the apartment. Christensen sexually assaulted her, tortured her, and killed her in brutal fashion - but I don't think Yingying was alive beyond a couple hours inside the apartment.
As far as what more could have been done - this is still a sore subject. Do I wish we would have done more? Of course - I wish we had done whatever it takes to find her. I still wish that. Nobody pushed harder for a landfill search than me. Even after the FBI said no, I begged and pleaded, whatever I needed to do, to try to get one of our agencies to do that search. I was pushing on that as early as the fall of 2017. The agencies all said no, for various reasons. I was not able to come to some peace with that (NOTE: coming to "peace" with something does not mean I agree with the result, or am happy...just that I can accept the rationale) until ISP and U of I did their extensive study on it. Searching the Danville landfill would have cost millions of dollars to search, exposed thousands of people to asbestos, medical, and toxic waste, risked environmental damage, taken months, and then cost thousands (or millions) of dollars more in litigation afterwards - all for perhaps a 1 or 2% chance of finding her remains if she were even there. That's a tough sell. Despite how tough of a sell that was, and despite the fact that Yingying's family was suing them at the time, I know the University really wanted to do the search. This was just too much risk for a vanishingly small chance of reward though.
As for searching outside of the landfill, certainly more could have been done, but that's not how the FBI operates. Had this been a state agency leading the investigation, then perhaps they would have marshalled the public to assist. I know everyone here wanted that. The reason state agencies sometimes marshal the pubic is often one of two scenarios: (1) they just don't have the resources to follow all the leads, or (2) they don't have any leads. Neither was the case here. FBI brought federal resources, and they followed every single lead. How much more would have been productive? Is searching for the sake of searching, even if there is no reason to believe the area to be searched would produce evidence, productive? I don't know the answer to that. I do know such searches pose risks when marshalling the public. C-U is in the middle of farm country. Having parades of people traipsing through farmlands in the summer and fall risked damaging crops, among other risks. Expending the necessary law enforcement resources to conduct such searches would have drained the agencies of the ability to investigate other crimes. Again, those are tough decisions. The FBI chose to let the public guide them through tips, and kept the investigation internal.
Even if she's not in the dumpster, I doubt he hid her somewhere near his apartment. There were extensive searches, of the type you suggest, in the areas around the apartment. The FBI and state agencies used dogs (cadaver and articles searching) throughout much of that area, and many of these areas were extensively searched. Ponds were dredged through, dumpsters dove into by agents, fields combed, empty buildings explored, etc. There was a lot more searching in and immediately around C-U than the public knew about.
Will she be found? Will anyone search for her again? I hope so! FBI is still following leads, so if something comes in, they will follow up. As I noted in a recent post, they dredged a pond and searched a woodline in northwest Champaign as recently as a couple months ago based on a new tip from after the trial. If she is in the landfill, finding her will require a new set of eyes, a technological breakthrough that would make searching landfills easier and safer, or some serious fortitude by the leadership of a law enforcement agency or a private / public partnership with significant resources.
