Chapter 32 Chapter two

Shortly after Don Bruce was raped and murdered, a detective from the Richmond Police Department, John Alderman, was called in to join us in investigating the case.“When you get involved in a heinous rape like this, there’s a sense of righteous outrage that sticks with you,” he told me. I said that I had already felt it, and told him the feeling of suffering all the time.I also told him that all people of conscience would be outraged by this case.I shed tears in my heart. We must know that those who handle the case cannot shed tears easily, otherwise it will affect the progress of the case.On this point, he and I are very clear in our hearts.What's the next step?This is very important to the Richmond Police Department and us.

We began to focus on investigating the few physical evidences we have. What does a little physical evidence mean?I understand very well in my heart, but we have to give Tang justice. In this way, we have to find the criminal facts from the only evidence, which is like finding a needle in a haystack. Tang's fatal injury was a stab wound to the heart.In the forensic laboratory, we found that there were two straight indentations printed on the pillowcase, which seemed to be the blade of a knife, with a jagged edge.I infer that the murder weapon may be a hunting knife. Usually, hunting knives are used for cutting, skinning, etc. when hunting in the wild. In addition, it also has the function of stabbing, but the requirements are not as strict as fighting knives, and hunting knives can have various shapes.Hunting knife is also a kind of survival knife, which exists for survival. It can be used to defend against enemies, as a tool, and to obtain food.

When I explain the purpose of this knife, I try to make my point as clear as possible, and then let my colleagues add. It is unscientific to define a knife as a kind of knife. Can fighting knives not be used to cut meat?Hunting knives can't be used for fighting?As I observed Don's jagged edge, all sorts of knife associations came to my mind.I think that regarding the use of knives, it depends on which side you prefer to hold in your hand.If it depends on the user's use, he will choose the type that matches the use as much as possible, so that better or more single effects will be achieved.

I explained this to my investigators, Thomas Tiller, Jim Dorton, and John Alderman.I told them that combat knives have a sharper tip and often have false edges, and the blade should not be too wide, as it is easy to break when used as a survival knife.The blade of the hunting knife is thin and sharp, and the blade is light.Those with the characteristics of both can be used as combat knives or as hunting knives.A sword-shaped combat knife with a thick opening is theoretically not suitable as a hunting knife, and a hunting knife without a false edge and a rounded tip is theoretically not suitable as a combat knife.Survival knives often have many accessories such as small fishhooks and flints, and the blade is thick. Of course, the blade can be thin and the tip can be sharp, but there are certain restrictions, otherwise the strength is not enough.In fact, regardless of factors such as convenience, practicality, and fragility, there is no problem with the interoperability of the three.

My explanation of the hunting knife is to inspire everyone's imagination about this case.Thomas and Jim also have a lot of research on hunting knives. They say that the materials of hunting knives are the best.Based on this, we temporarily assumed that the hunting knife in the hands of the criminal who killed Tang was the best hunting knife on the market, so we sent people to the market to observe various types of hunting knives. In addition, I found that Tang's pillowcase seemed to be able to pick up fingerprints, but because of the textile pattern on the pillowcase, it was impossible to perform any kind of fingerprint analysis, but in the end this regret was made up.One morning after the murder, I had just entered the office when Thomas told me the good news.Colleagues at the crime lab found a mutilated fingerprint in blood on a don pillowcase, in what might be the most significant discovery in recent memory.

Past case-handling experience tells me that fingerprints can be divided into three categories according to their shapes: one is bow-shaped, which is shaped like a bow; the other is hoof-shaped, which is shaped like a horseshoe; the other is Spiral, spiral-like shape. I once read a paper by an expert on trace science, which said: Among the 64 billion fingerprints, only one pair has the same fingerprint.Other scholars have said similar things.Therefore, no matter how the population increases in the future, no one's fingerprints will be exactly the same.This "no one is the same" principle, I believe it will not change.

On Don's pillowcase, the fingerprint was so faint that even the trained eye could not make it out.The ridges of the fingerprints are irregular.We looked at it under a magnifying glass, but the magnified texture of the fabric almost completely covered up the ridges.In this case, I've given up little hope for that fingerprint. Because there are ridges in the blot, that's all the incriminating evidence we have, but we can't enlarge it in every way we can.So little is known, and we'd love to get more evidence, but it's almost impossible. On the day of the incident, we also found a small amount of semen at the scene.Serum tests showed that the murderer's blood type was type A.This is also good news for us, because the clues of the case have not been interrupted after all, and we finally caught some clues of the criminal.This is at least a consolation to us.

At this point, we've excluded Don's boyfriend, and Don's neighbor who is on parole.Both of them were out of town on the day of the incident and had no time to commit crimes. Now there is only one person left, and we will investigate him as a key suspect.This was the same Robert who had been teasing Don with obscenities, and who had been detained several times for drug possession. When I knew that Robert's blood type was A, and it was consistent with the semen sample taken from the crime scene, I had an urge to win. I think the idea of ​​narrowing down the scope of the target to Robert alone is correct.But the guy also had an alibi that night, saying he was with his girlfriend that night.I think there is something strange in it, so we decided to continue the investigation.

As a result of the investigation, the fingerprints on Don's pillowcase did not match those on Robert's file.This again made me indecisive, at the time, we were using traditional photographic techniques, which, you know, were able to separate the ridges from the grain of the fabric to a certain extent, but in general they were not as good as they should be. We still cannot conclude that the fingerprints have been confirmed.We tried various chemical methods to make the fingerprints on the pillowcases more legible.But every time the fingerprints became clearer, so did the grain of the pillowcase.In this regard, we can say that we have racked our brains, but we have not made any progress.

I am very distressed, the fingerprints are there, we observe and study it every day, but no one knows how to peel it off.The fingerprints were among the blood on the pillowcase, which was textured, making it difficult to tell.If there were some way to make fingerprints identifiable, it would be as irrefutable in court as DNA evidence, if not more authoritative. As a result, the investigation was temporarily shelved. We hold an annual cryptic fingerprinting seminar, and all the forensics in Virginia will be there.This is basically a training session.And this time, a supplier will bring their imaging system to the venue to demonstrate to us.

I'm still skeptical about imaging systems because no one has used them in criminal investigations yet.But fingerprints found on pillowcases are so fuzzy, maybe this system will help us.I am looking forward to this moment with anticipation. My feeling at that time can be said to be the same as the fuzzy fingerprint evidence, but I have a kind of curiosity. The result is waiting for me ahead. I know that there are many trace identifications, and fingerprint identification is one of the trace identifications.Trace identification is the use of trace inspection technology to analyze, compare, and infer image traces related to crimes, and to draw conclusive opinions on whether they are identical or not. Fingerprints are unique, leave traces on objects, and remain unchanged for life. It can directly identify a person's identity.In judicial activities, in the criminal proceedings of suspected theft cases, fingerprint identification will play a very important role in confirming crimes and finding criminal suspects. However, there are also many problems in the judicial activities of identifying theft cases using fingerprint identification.Some argue that fingerprint evidence is unreliable, arguing that many of the fingerprints taken at crime scenes are so-called cryptic prints, meaning that the collectors have treated them with special chemicals or used ultraviolet light in order to "recycle" them lighting.This processed looming fingerprint is often incomplete, making it impossible to derive a unique pairing. Another reason is to declare two fingerprints to be identical, which usually requires a certain number of similarities between the two.Different jurisdictions have established different standards as to how many similarities are required, making the standard seem arbitrary.However, due to the limitation of various objective conditions, the conclusion of identity identification of judicial activity fingerprint identification cannot reach 100% accuracy, and this issue should draw our attention. I said to Thomas and Jim before going to the meeting: "In today's vague fingerprint seminar, we may find some kind of answer, although I don't know where this hunch comes from." Thomas and Jim, seeing me talking to myself, just sat on the edge and laughed without saying a word.I know, in fact, they are not easy in their hearts, they may be more anxious than me, they just don't want to add pressure to me. Thinking of this, I readjusted my thoughts. I believed that the imaging system brought by the supplier could really help us a lot, so I began to listen to their demonstration attentively. Image enhancement technology uses computers to identify patterns, such as the one on this pillowcase, and once the texture of the fabric is determined, it is removed, leaving only the ridges of a fingerprint.After 10 hours of testing, the murderer's incomplete fingerprints will gradually emerge. Imaging suppliers also use the information that changes drastically in the image and the principle that it is only related to high-frequency components, combined with the high-frequency enhancement filter designed by MATLAB, to enhance the image, and use time-domain histogram equalization on this basis technology, and then image processing.The test results show that the combination of these two technologies can completely process the detailed features of the image more clearly, sharpen the image, and its image enhancement effect is better than that of using any one of the technologies alone. My heart began to stir, and I saw Thomas and Jim's eyes light up.I cast a grateful gaze on the imaging technology suppliers. In the seminar, I also learned that image enhancement is the preprocessing of digital images, which can effectively improve the overall or local features of the image.The digital image is enhanced, and the method of combining histogram equalization in time domain and high-frequency enhancement filter in frequency domain is used to enhance the image. I was praying for Don in my heart, and it seemed that the case would be cleared up soon.Thomas and Jim seemed calmer than me, but they said they were not quite at ease.My heart also gradually calmed down. If we want to catch Tang's murderer, we must identify the fingerprints on the pillowcase. I thought again of Robert, the prime suspect in the case.He has a bad record of drug abuse. It is very important to know the source of drug money for drug addicts.However, there is no possibility of Robert murdering Tang to ask her for drug money. On the contrary, he killed and raped Tang. This method is appalling. I can't do without the theme of Robert's mental abnormality. If this case is really solved in the future and the criminal is really him, I still have to analyze and think about the role of his mental abnormality in this crime from this perspective. how much. But during Robert's interrogation, he kept saying that he had an alibi.The morning Don was murdered, he said he was with his girlfriend, but she told us that Robert wasn't with her all night. Regarding the contradiction between the two people's statements, both Thomas and Jim and I think this is the best opportunity to investigate the suspect.The three of us discussed together, starting with Robert saying that he had an alibi, to see if we could find some clues. Don was murdered around three or four o'clock in the morning on Saturday.This time is the time when people are most likely to fall asleep.Robert's claim to have been with his girlfriend all night seemed flimsy, as she said he "was off somewhere between three and four o'clock." The two people's statements were inconsistent, which brought benefits to our investigation and evidence collection, and my suspicion of Robert was even deeper.