The real-life detectives of today are every bit a match for Holmes, although it might be noted that they enjoy the advantage of modern equipment and instruments that Holmes knew nothing about. Modern science might make today's detectives seem a bit less glamorous, but their gadgets have greatly increased the reliability of crime-solving procedures.
Last fall, a plastic barrel was found dumped by the side of the road near the Shanchuku sanitary landfill just outside Taipei. Inside the barrel was a black plastic trash bag. Inside the trash bag was a dead body. A travel bag was found next to the barrel, and the condition of the body indicated that the victim had probably been beaten to death with a blunt instrument. No witnesses. No identification on the body. The case was turned over to Taipei City Criminal Investigation Department.
Start at the scene of the crime
According to American-trained forensics expert Li Chang-yu, there are four main elements in criminal investigations: the scene of the crime, physical evidence, information obtained through questioning, and luck. In a seemingly clueless case like the one described above, the first requirement is to inspect the scene where the body has been found.
Hsieh Sung-shan, Director of Forensic Laboratory, Criminal Investigation Department, Taipei Municipal Police Headquarters, recounts how the case was handled. The police first collected physical evidence. The fact that the plastic barrel was not brand new led them to deduce that it could very possibly have come from the scene of the crime. From the large size of the black trash bag, they inferred that it might have come from a place of business rather than a home. To find out the victim's identity, they checked to see who had recently gone missing in the local area, comparing the victim's physical appearance against that of each missing person. They were also lucky enough to find three fingerprints on the travel bag.
The police investigation revealed that the victim might be the missing owner of a hotel on the outskirts of Taipei. They searched the hotel and found plastic barrels similar to the one found by the roadside. The weight, size, and material all matched. They also found a bundle of black trash bags. After checking their shape, weight, and material, police determined that the bag in which the body was found had come from the same bundle.
The fact that the hotel stairway had recently been cleaned all the way to the 7th floor led police to suspect that the murder might have taken place there. In a 7th-floor office they found blood spots on a table leg and behind a chair. Lab analysis proved that the blood found there belonged to the victim. The police also found broken bits from an electric baton, thus confirming their suspicion that the victim had been killed with a blunt instrument. The broken bits were on the floor beneath the chair, indicating that the victim had probably been beaten to death with an electric baton while sitting in the chair. After obtaining further evidence corroborating the victim's identity, the police then began investigating the victim's acquaintances and checking who he had last seen before his disappearance. The fingerprints from the travel bag were eventually matched to those of a suspect.
Digging up the evidence
Says Hsieh Sung-shan, "This was one case where forensic science really paid off." In a criminal investigation, the police have to be more meticulous than the criminal. In this case, only a careful examination of blood splatters, fingerprints, plastic barrels, trash bags, and broken bits of plastic enabled the police to catch their criminal and bring him to justice.
According to Li Chang-yu, forensic science entails the examination of physical evidence to determine whether a suspect in a criminal case has actually committed a crime, and whether the crime can be proven in a court of law.
To obtain a rape conviction, for example, it is necessary to first prove that the victim was forced to have sex against his or her will. Physical evidence can be useful in such cases. Is the victim's clothing torn? Has the victim been injured? Is there evidence to connect the suspect with the crime, such as semen, fingerprints, or blood stains? Have hairs from the victim's cat been found on the suspect? Such evidence can pinpoint the identity of the perpetrator, help to reconstruct the scene of the crime, and provide a basis for evaluating statements made by the suspect.
Police departments are attaching increasing importance to forensic science. This trend is due in part to the fact that there has been a growing emphasis upon human rights and the need for courts to base their judgments upon hard evidence.
Preservation of human rights is key to social progress. The higher a society's standard of human rights, the more civilized the society. Nowadays, not only the victims of crime, but even suspects, are expected to enjoy certain human rights. All statements made by a suspect must come voluntarily, and conviction and sentencing are based primarily upon physical evidence and the testimony of witnesses.
The increasing importance of forensic science in this century, says fingerprint expert Liao Che-hsien, "is due in no small part to advances in science and technology." In the field of fingerprint analysis, for example, the matching of fingerprints had to be done manually back in the days before fingerprint databases were computerized. "It took forever, and we didn't get near as many matches as we do now." A lot of cases were never solved due to the difficulty of fingerprint analysis.
In 1986 and 1987, there was a rash of "butcher-knife robberies" in the Tainan-Kaohsiung area. The robber's modus operandi was to break into homes, use a telephone cord to tie up the man of the house, and then demand money. The perpetrator often raped women in front of their husbands. For a long time, police had absolutely no leads on the case, but eventually fingerprints were discovered on a refrigerator door handle. The perpetrator had taken a can of soda after his crime and carelessly left his fingerprints behind.
ID card from God
If the case had occurred not long earlier, before the fingerprints of all convicted criminals and military draftees had been entered into a computer database, "it still would have been extremely difficult to break the case even with the fingerprints," confides Liao Che-hsien. It wasn't until 1991 that a fingerprint database was computerized at a cost of over NT$100 million. It was this database that helped the police catch their criminal. "The butcher-knife robber had already committed over 70 crimes, including robbery, murder, extortion, and theft. If it hadn't been for the fingerprint database, I hate to think how many more people he would have victimized."
Forensic science continues to grow more important to the criminal justice system. The most notable achievement of recent years has been the development of DNA analysis. Some refer to DNA as "the ID card from God." It can be extracted from any cell in the human body. It doesn't matter whether the cells come from blood stains, semen, saliva, or bones. Furthermore, when compared with a DNA sample from a suspect, the accuracy of a match is virtually 100%. DNA analysis represents a giant advancement over the ABO blood typing of the past, which only provided a basis for ruling out suspects through the process of elimination.
Lin Yu-hsiung, a law professor at National Chengchi University, points out that when attempting to identify a dead body, police used to rely primarily on physical evidence found together with the body, as well as the word of relatives. Unfortunately, cases involving badly decomposed or mutilated bodies were extremely difficult to pursue. Now, however, if the police already have a DNA file on the victim, DNA analysis will yield a positive identification.
Certain centuries-old practices in China foreshadow the possibilities of forensic science. There is a story from the Ming dynasty (1368-1644) that mentions the use of a silver needle as a kind of "litmus test" for the presence of poison, while the practice of using one's fingerprint to sign contracts and other important documents dates back to the Tang dynasty (618-907). The rigorous application of scientific method to criminal investigations in China, however, began in 1946 when the government first established a modern criminal investigation system. China's first criminal investigation department comprised two divisions. One sent detectives into the field. The other was a crime lab. This crime lab included all the functions that today make up forensic science: a coroner's office, fingerprint analysis, trace evidence analysis, etc.
In the past, however, courts did not place a great deal of emphasis on physical evidence, and field investigations stressed the importance of getting a confession from the suspect. Forensic science did not receive a lot of attention back then.
It wasn't until the 1970s that forensic science began to come into its own in Taiwan. This came about primarily, says Professor Lin Mao-hsiung, "because of frequent trips back to Taiwan by the US-based forensics expert Li Chang-yu."
Li had graduated from the Central Police College (the forerunner of today's Central Police University) and served a stint as a policeman in Taiwan before enrolling at New York University, where he obtained both Master's and Ph.D. degrees in forensic science. He then became a professor of forensic science at New Haven University in Connecticut. Tremendous progress was just then beginning to take place in the field of forensic science in the United States. State law enforcement authorities in Connecticut and many other states had established their own forensic departments. In a country like the United States, which stresses the rule of law, the courts attached great importance to the results of forensic science. After joining the faculty at New Haven University, Li used the university's chemical analysis laboratory to help the police investigate criminal cases on numerous occasions. In 1979, the Connecticut state police hired Li outright as their senior forensics expert, and he then rose through a number of positions to become the head of the entire Connecticut state police force in July, 1989.
Over the past 20 years, Li has stayed in close contact with Taiwanese law enforcement circles, and it was due to this relationship that Taiwan law enforcement agencies began in the 1970s to send people to the United States to study forensic science. Li himself often travels to Taiwan to meet with legal and law enforcement professionals. A consensus has gradually emerged in jurisprudence and law enforcement circles concerning the importance of forensic science.
According to forensics expert Weng Ching-hui, police departments formerly attached little importance to the support activities of crime lab specialists. Later on, however, forensic science began to assume a greater role in criminal investigations, and it often gave rise to conflict between opposing viewpoints.
Weng had just graduated from the Central Police College in 1975 and gone to work in the forensics section when he was called upon to review the evidence from a shooting. A detective presented him with a gun and several slugs and asked for a ballistics test. The detective informed Weng that a suspect had already turned himself in for the crime. Weng was only expected to review the evidence and close the case. Weng's ballistics test, however, indicated that the gun held in evidence was not the one used in the murder, so he refused to close the case.
The displeased detective was convinced that Weng was deliberately being uncooperative. More than a year later, however, police recovered two other guns used in crimes, and ballistics tests revealed that the gun used in the third crime was the same one used in the 1975 shooting, thus proving that the gun turned in by the detective in 1975 was not used in the murder he had been investigating. It turned out that each of the three guns had been used in a number of crimes, and the police followed the leads to solve them all.
The witness as disinformer
Weng Ching-hui explains the principle behind ballistics testing: "Due to wear and tear on machinery during the manufacturing process, every single gun leaves a unique pattern of minute striations on bullets as they leave through the rifled barrel. It is these marks that we examine in a ballistics test." These striations, says Weng, are to the gun what fingerprints are to people.
In the past, police relied heavily upon eyewitness testimony to obtain criminal convictions. The problem with this approach is that sensory perception isn't always reliable, and is sometimes the source of egregious errors, as both Eastern and Western philosophers have noted for centuries. Forensic science has been known to prove eyewitnesses totally wrong.
The murder of prosecutor Chang Chin-tu in Kaohsiung is an excellent case in point. According to Weng, there were three eyewitnesses to the murder. Furthermore, one was a judge and the other two were prosecutors. All three witnesses stated that the victim had been shot by a single assailant. Weng emphasizes, "All three witnesses were professionals from the criminal justice system." They understood that the court would place great importance upon eyewitness accounts and physical evidence, and that they could be held accountable for their statements. It seemed like an open-and-shut case: one gun, one killer.
The forensics department, however, questioned the eyewitness accounts. How could the six slugs and eight casings found at the scene have come from a single gun? Says Weng, "It was clear that more than one gun had been used, and it seemed quite possible that there could have been a second assailant." The case was solved, and it turned out that the crime had been committed by two gunmen using two guns. The details of the crime were the stuff of cinema. "After the first two gun shots," Weng explains, "a second gunman emerged from behind a garden wall and shot Chang Chin-tu in the thigh. The three witnesses were all diving for cover by that time, and no one noticed that there had been a second gunman."
Say no words, speak no lies
Weng asserts that physical evidence is more reliable than eyewitnesses. "It doesn't say a word, but it tells no lies, either." According to Li Chang-yu, "Eyewitnesses cannot possibly remember all the details clearly, so they invariably invent plausible scenarios in their minds to fill in the gaps. These details are invented subconsciously. On top of that, people often misperceive sights and sounds in the first place. The result is that eyewitnesses almost always make mistakes." These problems of perception and memory are part and parcel of the human condition.
Forensic science questions the validity of our sensory perceptions. What's more, an experienced forensics expert isn't fooled by the ruses that criminals employ to throw investigators off the track.
Forensic science played a key role in a massive street protest lasting several days that almost led to the ouster of former Premier Hau Pei-tsun. Members of the tangwai movement (an unofficial group that opposed the ruling party during the period of martial law, when opposition parties were outlawed) showed reporters the bloodstained T-shirt of a protester whom they claimed had been beaten by the police. The authorities were accused of police brutality, and a huge photograph of the bloodied man appeared in the newspapers, drawing the concern of human rights organizations abroad.
Although street protests had already come to an end five days earlier, the person's wounds could still be inspected, so Weng called for an examination. What they found was a shallow incision in the nape of the neck no more than two centimeters long.
A blood splatter analysis revealed that the blood appeared to have been smeared by hand across the T-shirt and the victim's forehead from the lower left toward the upper right, rather than from the top down as one would expect from a bleeding head wound. The two or three drops of blood found on the waist of the pants had dripped onto the fabric while the pants were in a horizontal, rather than vertical, orientation. "Regardless of whether the victim was lying down or standing at the time the blood splattered onto the pants," notes Weng, "there is no way to imagine blood dripping from a head wound onto the pants at that angle." These facts led Weng to conclude that the blood was fake, and had perhaps come from an animal.
Blood splatter analysis is a common means of determining how a victim has been attacked. The key clues that forensic specialists look for are the shape of the blood splatters and their direction of travel. "If the splatters are round, it means that the blood did not drop from very high up. If the periphery of the drops are jagged, it means that the blood dropped from a height of at least 11 inches. If they're in the shape of an exclamation mark, it's an indication that the blood dropped at an angle, and was splattered in the direction in which the dot in the exclamation mark is pointing." Li Chang-yu further explains that when blood splatters in the shape of an exclamation mark, it means the person has been stabbed with a quick knife blow.
Ever since about 1970, detectives have relied heavily on blood splatter analysis to determine the facts in a crime case. According to Weng Ching-hui, there was once a soldier who cut off his little finger and claimed he had been injured by a robber. His hope was that the injury would get him out of the military service, but the blood splatters were not in the shape of exclamation marks. Rather, they were neat little circles. According to a local police officer involved in the investigation, "It was obvious that he had sat there slowly cutting himself. You could tell right away that he was lying."
Make the clues count!
The main reason for the development of forensic science has been to apprehend criminals and see that justice is done, and the quickest way to induce a criminal to confess a crime is to show that you have irrefutable evidence. In addition to the "traditional" types of evidence (murder weapon, dead body, fingerprints, etc.), police at the scene of a crime cannot afford to overlook footprints, shoe prints, tire marks, blood stains, saliva, semen, ear wax, hair, or trace evidence (such as dust and pollen).
For all its usefulness, however, forensic science is not a stand-alone criminal investigation tool. Forensic findings must be corroborated by other observations if they are to be helpful in criminal investigations. To illustrate this point, Liao Che-hsien mentions a case in the Taipei suburb of Chungho in which a robber left fingerprints behind on the victim's motorcycle helmet. When the evidence was presented, however, the suspect claimed that he lived near the victim and must have accidentally brushed his hand across the helmet. Because there was no other evidence to support the fingerprints, the suspect could not be proven guilty.
Weng points out that if the detective investigating the crime had taken note of the position and orientation of the fingerprints, it would probably have helped the investigation tremendously.
Prosecutors, police, and forensic examiners must spare no pains to take maximum advantage of the physical evidence from a crime scene if they are to avoid letting key clues slip right through their fingers. A police official complains that he once saw a coroner use the same scalpel in the examination of two different bodies, thus contaminating the evidence. And there was the case of a high-ranking police official who, seeking to trumpet a police department success, led a pack of journalists to a crime scene. There he picked up a gun that had not yet been sealed in an evidence bag, and showed it off to journalists. In another flagrant violation of procedure, a prosecutor once asked a suspect to place his foot into a footprint in order to check whether it matched. Says the police official, "It would have been devastating if this destruction of the evidence had led to a ruling of not guilty for lack of evidence." It isn't just the general public that has a fuzzy understanding of how to conduct a proper investigation; even some law enforcement professionals have problems!
Crystal ball
Forensic techniques fall squarely within the realm of science. Says Weng, "Forensic science is very black-and-white. What's there, is there. What isn't, isn't." The practitioners of this science, on the other hand, are anything but black-and-white. Although the courts have come during the 20th century to put much greater emphasis on direct evidence, human foibles still influence the manner in which forensic science is put to use. Our judgment is clouded by preconceptions concerning race and religion, and we are even subconsciously swayed by a feeling of reverence for well-known public figures.
In the sensational murder case of Nicole Brown, ex-wife of former NFL star O.J. Simpson, blood at the crime scene was matched to Simpson's through DNA analysis. The defense lawyer, however, succeeded in getting the evidence thrown out of court. The defense contended that the blood sample had been contaminated on its way to the laboratory, and further claimed that the police had collected the evidence illegally in the first place. It is thus apparent that even when forensic science provides overwhelmingly strong evidence, it does not always guarantee a conviction.
The importance of the human factor cannot be overlooked. No matter how sophisticated forensic techniques are, and no matter how advanced scientific instruments may become, the key to success will always be how well the practitioner makes use of his tools. The core elements of scientific criminal investigation are broad knowledge, finely honed powers of observation, and a combination of bold imagination and cautious search for proof.
Weng illustrates this point by recounting a case involving the theft of numerous paintings from the home of the famous painter Ou Hao-nian. The thief was very professional. Just about all the paintings had been taken, and the police were at first totally stymied in their efforts to find a fingerprint. When Weng went to inspect the crime scene, however, he was intrigued to find one lone painting, the artist's favorite, still hanging on a wall. It seemed impossible to Weng that a knowledgeable art thief would not know of such a famous painting, so he climbed up a ladder to take a closer look. It turned out that the artist liked the painting so much that he had anchored the canvas to the wall in an acrylic base before mounting the frame. "We later took a closer look at the painting and found three very clear fingerprints on the upper right-hand corner. The thief had tried to steal it, but was frustrated by the acrylic base, so he took off his gloves and attempted to pry it off the wall. That's when he left behind the fingerprints." It was these fingerprints that enabled the police to crack the case.
The uncanny ability of the police to solve difficult cases has led some to quip that investigators have a crystal ball in their possession. To be sure, forensic science makes the crystal ball work better, but the crystal ball itself is something else entirely-the careful reasoning of seasoned investigators.
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The examination of blood patterns at a murder scene has become a highly developed science. Blood splatter experts study the shape and location of blood drops to determine how the crime occurred.
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A dead body went five days undiscovered in this apartment. Suicide or murder? For forensic experts, inspecting the scene of the crime is all-important.
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Every gun has a unique set of "fingerprints" that can lead investigators to the criminal.
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The requirement to protect the human rights of criminals is one of the driving forces behind the development of forensic science. In this photo, arrested suspects are put on show along with the evidence, a common but controversial practice in Taiwan. (photo by Wang Ying-hao)
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No two persons have identical fingerprints. The establishment of computerized fingerprint databases is one of the cornerstones of forensic science.
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In the early hours one morning in April, a man was shot to death in the township of Linkou, Taipei County. Forensic experts rushed to the scene to collect evidence. (photo by Ke Cheng-hui)
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A careful examination of the physical evidence is the first step in any forensic procedure. It takes considerable expertise to find a good set of fingerprints.
The requirement to protect the human rights of criminals is one of the driving forces behind the development of forensic science. In this photo, arrested suspects are put on show along with the evidence, a common but controversial practice in Taiwa.
No two persons have identical fingerprints. The establishment of computerized fingerprint databases is one of the cornerstones of forensic science.
In the early hours one morning in April, a man was shot to death in the township of Linkou, Taipei County. Forensic experts rushed to the scene to collect evidence. （photo by Ke Cheng-hui）
A careful examination of the physical evidence is the first step in any forensic procedure. It takes considerable expertise to find a good set of fingerprints.
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