Some time ago, in the "Hangzhou Woman Disappearance Case", in order to find physical evidence, the police spent a lot of manpower and time to find human tissue in the septic tank in the community. For most disappearances, it is particularly important to find the victim's body tissue as physical evidence to determine life and death, otherwise it will usually become a pending case.
This can't help but remind people of the "missing flight attendant case" cracked by Li Changyu, a Chinese-American and criminal forensic expert. In this case, the husband of the murdered flight attendant, Richard, was a former CIA worker and also had anti-reconnaissance experience. Although there is a suspicion of major crimes, there is a lack of evidence to prove that the murder occurred. After Li Changyu took over, starting from the clue of the broken wood machine provided by the snowplow driver, stripping away the cocoon, and finally found ironclad evidence of Richard's killing of his wife in the lake: 2660 hairs, 69 small human bone fragments, a truncated human skull, a small nail...
Today, with the development of DNA genetic factors, large databases, and artificial intelligence, there are diversified methods for cracking cases. But in 1986, the level of science and technology was not so developed, what did Li Changyu rely on step by step to find the truth and crack this case?
Recently, the reporter of this magazine interviewed Li Changyu and listened to him tell the most complete details of the cracking of the "missing flight attendant case" that year.
The following is Li Changyu's dictation
Li Changyu (Photo by Huang Yu)
I got my Ph.D. in biochemistry from New York University in 1975. Although my doctoral supervisor, Dr. O'Jowa, was a Nobel Laureate, instead of following in his footsteps as a biochemist in his career choices, I somewhat dramatically chose the profession of forensic science, which was not taken seriously at the time.
In 1975, I was hired as an assistant professor of forensic science at the University of New Haven, and four years later, I was invited to serve as director and chief forensic expert at the Connecticut State Police Court Science Laboratory. At first, we did a lot of seemingly fun cases that had nothing to do with homicides, but now I understand that these cases are important to the safety of society and the lives of people.
For example, on Halloween in the United States, many people with mental illness or social disobedience will put needles, blades and even poison in candy, children knock on the door to get candy, go home and eat it, some children go to the hospital, and some are seriously injured. To this end, the staff of our laboratory has specially designed the confectionery safety inspection process. This is a small matter on the surface, but it has a great relationship with social security and people's health.
Figure | Photo network
We also did some historical artifacts, and someone donated a table lamp to the Pittsburgh Museum, and the donor actually said that it was a "human skin lamp" from a concentration camp during World War II. The museum immediately contacted me after receiving it, and it was determined that it was really human skin, and it was three different blood types, which were made by Germans during World War II with Jewish human skin. So, our work also proves the history of the Nazi massacre of Jews from another perspective.
In my many years of case-handling experience, the "missing flight attendant case" is one of the well-known cases that I handled, and now countries around the world still use it as a classic case-solving example teaching, and that case used 16 different forensic science majors to solve the case. Solving a crime is not like a movie, it needs to rely on the team, the key lies in how to unite the team. Each team member has expertise and will make some contribution in the professional direction, and we have to think about how to add up all the test results to reach a conclusion.
The missing flight attendant, named Helen, is Danish and served as a Pan Am flight attendant before her disappearance. Her husband, Richard, was a former CIA affiliate and a pilot at the time of the crime. He had a very high IQ test score in school that year and was a very smart person. Helen was his third wife, and Richard was married to foreign wives who had no relatives in the United States and were gone. Richard has been having affairs since marriage and has committed domestic violence against Helen, who has hired a divorce lawyer and is determined to divorce Richard.
Helen with her husband and children
The disappearance occurred a week before Thanksgiving in November 1986. Early this morning, the man Richard told their nanny to dress the child quickly, he was going to send the children to Richard's sister's house, Helen would meet the children there, but the nanny did not see Helen there; Richard told his sister that he said to pick up the nanny and the children at four o'clock in the afternoon, but he did not come that day, until the next night to pick up the child and the nanny; Helen's good friend Anna talked to her every day, but this day could not contact Helen, so he asked Richard Helen's whereabouts, Richard said his wife was out of town.
A few days later, the nanny accidentally saw a blood stain on the bedroom carpet, and she wanted to take time to clean it, but a few days later she found that the bed had moved, and the sofa and carpet were missing. Her sense of foreboding grew stronger and she resigned quickly, but told Helen's friends of her suspicions.
The following week, neither the nanny nor his good friend Anna saw Helen again. Thanksgiving is very important to Americans, and Helen, who has always been extremely responsible for children, still did not appear; after Thanksgiving, Helen was going to fly a long-distance flight as planned, the company called to ask, Richard said that she had already gone to work, she was driving, and the company did find her car in the parking lot, but it was empty.
Illustration: Old cow
Helen's best friend Anna called again to ask about Richard. He replied that Helen might have gone back to Denmark to see her mother; Anna had called Denmark when she flew to Germany, but Helen's mother said she hadn't returned for many months. Combining the above factors, Helen's friends suspected that Helen had been killed and went to the police.
When the police came to question Richard, Richard was very calm and asked, "How do I know her whereabouts?" She may have run away with the young man. The reason he said this was that he was more than ten years older than his wife. The police asked him if he could get a lie detector, and he agreed. The first lie detector passed, and Helen's friend and mother complained to the prosecutor that Richard had worked as a volunteer police officer at the police station and that there might be a harboring phenomenon in the police. So the prosecutor ordered the state police to give Richard another lie detector test, and he passed several lie tests.
One tester later said, "He was the least responsive subject I've ever seen." "According to the common practice in the Judicial Community in the United States, the discovery of the corpse is the necessary evidence to prove that the murder occurred. Helen disappeared for such a long time, although everyone also suspected Richard, but one could not find the body, and the other was that Richard did not show any flaws, so this case became a headless case, and it has been left there, and Helen has become a missing person. The police later even tended to think that Helen had eloped with the young man, that her friends had nothing to do with her, and that she had watched too much on forensic television.
Dissatisfied with the attitude and ability of the local police, Helen's friends approached the Connecticut State Prosecutor and the Department of Police's Major Crimes Unit. The prosecutor general came to me and asked if this case could be transferred to us, and they really had no way - now that there is a big database, artificial intelligence may be easier to solve the case, but at that time, there was no such thing, how do we rely on manual to solve the case?
People don't disappear out of thin air. If they were killed, there were only a few places where the body could be hidden: buried on the ground, thrown in the water, cremated, or placed in a refrigerator. So our first step is to take the testimony of all the witnesses the police have asked and find the keyword (keyword).
One witness was a snowplow driver. He said he saw a man dragging a large sawmill at four o'clock in the morning on a snowy night, and he kindly asked, "How do you drag such a big sawmill with such a big snowstorm?" Hurry home. Unexpectedly, the man actually raised his middle finger at him. The snowplow driver was very angry, so remembered this strange man.
Stills from "Crime Scene Investigation"
I thought, in the middle of the night on Thanksgiving, who is dragging a big wooden crusher to do what? So I asked the snowplow driver if he remembered what the wood crusher looked like. He painted it for us. So we sent criminal police to investigate, and found that there were only four stores in the whole of Connecticut that rented this wood crusher, but during this time, no one rented it. As a result, I found a wood crusher shop in Newark and found that there were people renting, and one of them was Richard. We asked the owner, who said that usually people rent the machine and it was dirty and smelly when they came back, but when Richard returned, the broken wood was clean.
We sent the police officers to ask Richard, who said that his family had 18 acres of woods, and it was not surprising that he had rented a sawmill to saw trees, because he had liked to be clean all his life. There was no evidence of the next step, and we couldn't do anything about him, and we couldn't find anything when we went to his house to search, because the whole furniture was changed.
In order to sort out the clues, we need to rebuild the site and see what the bed in his bedroom is like. Usually we recreate it through a family photo album, but very few people take pictures in their own bedrooms, usually in the living room, in the yard, with dogs and children. No way, we had to turn to Helen's best friend Anna. Initially we sent a policeman over, but we were scolded back. Anna said there was a Christmas party at home, don't come to her for trouble; but then we sent a young and handsome policeman to knock on the door, and she immediately said, "Well, wait for me for ten minutes." "You see, the various details in the case are also very interesting.
Stills from Murder on ABC
As soon as Anna arrived at the police station, she said, "Dr. Lee, you are my idol." I asked her if she could help me, and she readily agreed. A few hours later, the work was completed, and Anna said that it was too interesting to help us rebuild the site, and she knew that she would also learn this major. She offered a new clue: Richard never washed clothes or sheets. Through investigation, we found that There were a lot of sheets hanging in Richard's basement, and after the receipt and examination, unsurprisingly, these items had a bloody chemical reaction on them, and the blood type was also consistent with Helen's blood type.
Although Richard's suspicions are getting bigger and bigger, there is still no way to solve the case without finding Helen's body. We think and reason again based on a few known clues: If Richard had broken the body with a wood crusher, where would he have chosen to dump it? I remembered a clue: the snowplower had met Richard that day on a fork in the road that led to a lake called Yola.
The story of the search is long, and for comparison, we bought a pig, crushed it with a wood crusher and threw it on the ground to do parabolic distance measurement experiments. Then we decided to go to the lake to fish, and soon found a few bones, but the examination found that it was deer bones and not human bones. The officer said he had found a chainsaw and asked me if I wanted to keep it, but I thought about it for a moment and replied, "Bring the chainsaw back!" ”
We removed the chainsaw and checked it, and found that the number of the chainsaw had worn out, so we used chemical methods to make it dominant, and after a few seconds we found its number — decades later, I still clearly remember that the string of numbers was E591616. We immediately called the chainsaw company and asked who was the chainsaw sold to? The chainsaw company said it had been sent to the Newark Distribution Center; the Distribution Center said it had been sent to a sawmill shop in Connecticut.
The police officer in charge of investigating the clue reported that the owner of the sawmill shop was sick in the hospital and had a heart attack, so I quickly called the hospital and said, "Don't operate first!" Let me ask, who is this E591616 sold to? The owner replied that he did not know. I asked if there was a receipt, and he said it was in a shoe box under his bed.
Later, we found the receipt in the shoe box of the boss's house, checked it, and unsurprisingly, the buyer was Richard. We opened the chainsaw again and found that there were broken bones, flesh, and skin inside, and then we asked experts to study the bones and fibers. Finally, we found 2,660 hairs, 69 small human bone fragments, a truncated human skull, a small fingernail, and so on in the snow in the lake.
Stills from Sherlock
Many people thought that I had the foresight to be keenly aware that the chainsaw was an important evidence of a murder, but in fact, I had two thoughts at the time, one was why such an expensive thing was thrown away? And even if it is not evidence of a homicide, our laboratory just does not have this thing, and it can be used.
This is the first case in the United States that has no body and relies on DNA to solve the case. The case was a classic, and it was later made into a documentary, a TV series, a movie. One of the episodes is to put people in a wood crusher and destroy the corpse.
Some people also say that whether or not this case can be solved has too much to do with the subjective efforts of the case-handling personnel. My feeling is: you must lead by example and go to the scene of the case yourself. The weather is very cold, the snow is very thick, if you don't go to the scene, just let the staff look for it, find it and report to you, then they will definitely look for it and leave. And what we did at that time was to divide the lake surface that was blocked by heavy snow into a thin grid and dissolve every inch of snow to search. Plus, you're going to bring together experts from all walks of life. To be the top experts in the industry, everyone has a little bit of pride, but we all cooperate very well, and the field and the in-house work closely together.
In 1989, the jury finally found Richard guilty of first-degree murder and sentenced him to 99 years in prison.
Nearly 20 years after serving his sentence, he once wrote me a very short letter: "Dr. Lee, you are the only one to tell the truth in this trial, and I agree with your analysis, but it was an accident. "I didn't reply to him and I also hope that, as he said, it was really an accident. If couples attach importance to marriage and tolerate each other, many tragedies in the world can be avoided.
I recently returned to the mainland to give a lecture, and many people have mentioned the Zhang Yingying case to me and asked me for my opinion. I was not directly involved in this case. All I can say is that if I were to handle the case, I would never arrest someone first. The kind of car driven by the criminal is more than a dozen in that area, checking the itinerary of each car owner on the day, and accessing the camera, driving record, car fuel record, to see where it has been, how many times it has added oil, and where it can drive as far as possible. Do a big database and artificial intelligence analysis nearby, and you can get a rough idea of where he is. Evidence of micronutrial objects, such as blood on hair and DNA, was then collected in the suspect's car.
People's bodies are always hidden in those few places, but as soon as you arrest someone, the suspect will not talk about it, because as soon as you open your mouth, you will confess your guilt. The only evidence the police had at the time was secret recording, which was the FBI's strongest method, installing a secret tape recorder, but the evidence was just that. Where Zhang Yingying's body ended up is also a mystery, which is indeed a pity.
Forensic science is from traditional comparison, chemical analysis, to the current testing of DNA genetic factors, to large databases, artificial intelligence... Constantly improving, so we must also continue to learn how to use new scientific and technological means to solve cases. If you still use the traditional method, you are out of touch with the times. Forensic science is a very technical industry, and although I am no longer working on the front line, I must also pay attention to the latest scientific and technological achievements. My own experience with this is:
First, we must have ambition. I read every day, read a little book every day, learn something new;
Second, the need for work. We founded the National Cold Case Center in the United States. Local police agencies have handed over some unsolved cases to our "cold case center". Since the old method can no longer solve the case, we must have a new way to solve the case. So what's new? You have to think about DNA sequences can be? Or maybe we found some algae from the victims, and the algae in each pond is different, what is the difference between them? This knowledge must be understood;
Third, I often go to countries around the world to train and teach, of course, I can't talk about things from decades ago, I must talk about some new ways to solve cases. Artificial intelligence is the hottest now. Artificial intelligence is very simple, just like our traditional logical analysis, how to use a large database, use a machine to help us solve the case.
For example, in the room where we are chatting now, after you are gone, use the machine to analyze, and the machine may not be able to analyze how many people are here before. If I had come, I might have been able to analyze what the situation was, from the design, from the teacup, from the direction, from the footprints on the ground. Then from the traces left on the couch, look at the weight and even the shape of the person, whether it is a boy or a girl, or leave a hair here, you can reconstruct the previous situation.
According to the U.S. Department of Justice, an average of 37 percent of homicides in the U.S. go unsolved each year. Behind every case, there is at least one innocent deceased, as well as a family that has suffered the loss of a loved one. For example, in Helen's case, in fact, Richard's first two wives have not been found until now, and can only be listed as "missing persons".
Eighty thousand people go missing in the United States every year, which is a terrible number. When I was invited to give a lecture at the International Year of Missing Persons last year (2019), my wife went with me and was sad to hear a lot of stories. Some people disappeared because of dementia in the elderly or children who ran away from home, and some may have returned later, but many people are missing.
I think I fell in love with this profession only because I had a thought in my heart: "Who will speak for the dead?" "But no matter how developed the technology is, it is difficult to resist the evil of human nature." How to suppress the evil of human nature may be a larger and more universal problem that we all have to face than the science of forensic science.
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