Chapter 16 Chapter Four

On May 7 of the following year, seven months after the disappearance of Shirley Dugay. There's an old saying in the RCMP that we can catch whoever we want.But this time, we only caught the cat we wanted to catch. In the end, Snowball was caught, and it appeared to be as cunning as its master.It was taken to the local veterinarian's office, which had an Animal Hospital sign outside the door, where we took the necessary blood samples from Snowball. To avoid accidents, when Dr. Jane Bond in the hospital drew blood, two government officials stood by and waited to take the blood sample.The blood samples and cat hair from the leather jacket were then sent to Dr Stephen and his research team by hand.

One of the hairs still had roots, and the doctor cut it into pieces and put it in a buffer solution that dissolves everything except DNA.After amplification, or replication, scientists have enough DNA to test. The doctor then compared the DNA imprint of the hair found in the leather jacket to the DNA in Snowball's blood sample. The genotype of each genetic marker in the hair matched the genotype of the same genetic marker on Snowball's body seamlessly.The only way this could happen is if the hairs came from the same cat. However, Prince Edward Island is isolated and there are thousands of cats living on the island.If this were the case, DNA matching would be useless.

Of course, these hairs cannot come from all the cats on Edward Island.But what if 25% of the cats on the island, or 10% or even 1% of the cats, have this DNA print?So the next question is, what are the odds of this pattern appearing? So Dr. Stephen needs blood samples from at least another twenty cats.He also talked about cat inbreeding and cat population segregation or pure cat-cat hybridization, could this lead to another cat on the island with the exact same genetic print as Snowball?Because inbreeding is close breeding, just like half-parents and half-parents.The population refers to all individuals of the same kind of organisms occupying a certain space within a certain period of time.Individuals in a population are not mechanically assembled, but they can mate with each other and pass on their genes to their offspring through reproduction.The population is also a basic unit of evolution, and all organisms in the same population share a gene pool.

Our task of collecting blood samples from 20 cats has not yet been completed. Even if the number of cats is enough, it will take some time to transport them from Canada to the United States. During this time, we are in Dr. Stephen’s laboratory and continue to listen to his introduction about cats. We don't quite know where modern cats evolved from?For what reason and when did it leave its birthplace and migrate to other continents?How many species of cats are there?What is the relationship between them?For these new subject knowledge, I have to listen carefully. "First, we need to determine the distribution of each cat species and where the fossil remains of their ancestors appear. Of course, we also need to look at the cat world from the perspective of a geologist. Geology Scientists infer the rise and fall of sea level based on the composition of the sediment. When sea level falls, land bridges connect continents and mammals can migrate to new areas. When sea level rises again, continents Animals are once again isolated. From the analysis of vertebrate research results, the isolation between continents and islands just provides the required conditions for the genetic drift of a population and the eventual formation of new species. When genetic drift When the degree is large enough, the population can no longer mate with the offspring of the previous relative population. At this time, reproductive isolation occurs, which is the sign of new speciation. With these understandings, we can provide cats with According to the historical migration of cats, a reasonable route can be constructed. According to the fossil records, most of the researchers believe that a cat called false cat that lived in the European continent ten thousand years ago is the modern cat The most recent common ancestor of family animals. The appearance of false cats is not the first cat that appeared on earth. There is a large saber-toothed cat called hunting cat that appeared as early as ten thousand years ago, but their descendants Almost all became extinct. However, according to our recent molecular studies, all modern cats originated from a false cat that lived in Asia 10,000 years ago. Although it is not certain which species this ancestor cat was , but we believe that the 'Adam and Eve' of today's cat species arose in this ancient population." Dr. Stephen concluded in this way.

Fur aside, the differences between felines are very subtle.Even for experts, distinguishing the skulls of lions from tigers is a challenging task.Genetic studies conducted by Dr. Stephen over the past few years have also been unsuccessful in definitively classifying these cats. In recent years, in the field of genome sequencing of various organisms, the Human Genome Project and high-tech DNA detection technology have taken the lead, setting off a technological revolution.Dr. Stephen said that it is these scientific and technological developments that also provide some very valuable methods for the classification of cats.Now using these new techniques, with the help of colleagues from other institutes, a clear and concise family map of the cat family has been constructed.

"We've compared the exact DNA sequences of 30 genes in living cat species, and we've identified the clades in the lineage map. We'll then use fossils with exact dates and 'molecular clock' tests, which, of course, "Methods can estimate when one species evolved to diverge from another based on the degree of divergence between specific genes, and in doing so, in order to know when each branch formed. These findings are the first to show us clearly that different sizes relationship between cats and advances our understanding of how and when these top predators migrated across the world."

After saying this, blood samples from twenty cats were sent to Dr. Stephen's laboratory.Through genome sequencing, the germlines of cats have been successfully delineated. DNA studies divided the twenty cats into eight distinct clusters.We are encouraged that these 8 lineages based solely on molecular assays are consistent with other observations that species within the same lineage often have morphological, biological, and physiological characteristics unique to this group .For example, the large howling cats (lions, tigers, leopards, jaguars, and snow leopards) are all able to roar because the hyoid bone that supports the tongue in their necks has not yet fully ossified, but other species Animals of the same family do not necessarily have such characteristics.

Dr. Stephen's comparison of the gene sequences successfully divided the twenty cats into different species and revealed the order in which these species appeared.But we need two other pieces of information to refine our guesses, find out where these cats originated, and understand how their current distribution came to be. The DNA prints of the twenty cats showed a rich diversity of genes.Members of a specific community of a species, due to a large number of slightly different common ancestors, will also show differences at the chromosomal level. This property makes the group more tolerant to disease and ecological changes. sex.

The genetic diversity of these cats also represents variation in genetic structure within and between populations of organisms.That is to say, each species includes several populations composed of several individuals.However, due to mutation, natural selection or other reasons, various populations often show their differences genetically.Therefore, some populations have gene mutations that are absent in other populations, which we call alleles, or alleles that are rare in one population may be abundant in another population. 'Genomic pawprints' in feline DNA clearly show how cats are related.

The odds were calculated that the cat hair found on the leather jacket belonged to another cat other than Snowball: 1 in 70 million.This is good news, I quickly dialed Werther's phone, wanting to tell him the good news.However, he has a bigger happy news waiting for me. Seven months into the search, a fisherman stumbled across the last piece of evidence in the case.To be precise, in the twenty-eighth week of Shirley's disappearance, a fisherman walking along the banks of the Amor noticed a strange pile of branches on a stretch of bank.He removed the branches and found what appeared to be a body buried underneath.

The tomb was dug very shallow, just enough to cover the body, and the deceased was very thin.We know Shirley is less than five feet tall and weighs less than 100 pounds, so obviously, this could be Shirley Dugay. Two police officers went to check the situation. At this time, it started to snow in the sky. Only one of the two police officers who went there was wearing a rain jacket.The body was partially exposed, and one of the police officers took off his only warm rain jacket to cover the grave, fearing that the body would be drenched in snow. To my amazement, the burial place of the body is almost exactly the same as the psychic prediction made by our police department.Very close to the water, under the pine trees. What luck!They found her as soon as they went.A policeman told me that if it had been two or three weeks later, or longer, it would have been much harder to identify Shirley than it is now, because by then the ground would have started to melt. We know that the chances of finding Shirley alive are very slim.But we are also very relieved to have found Shirley's body.In a sense, at least we can do something for Shirley, we pray for her, that their family can be reunited, at least this can now be closed. An autopsy proved Shirley died from blunt force trauma, which corresponded to blood splatters in her car.Her nose was broken and her jaw was broken in three places and one of her front teeth was found in her lung. Doug was charged with murder and arrested. We found bloodstains of both Doug and Shirley in Shirley's car. Why did he kill? In Doug's confession, he admitted that he had threatened Shirley in the letter that he would kill her if she got custody of the children. The crux of the problem is the custody of the child. He also wants custody, but is he a good guardian?In Canada, separated couples can provide for custody and custody of their children in their separation or divorce agreement.Of course, even if there is such a separation or divorce agreement, the court may not recognize the validity of the separation agreement based on the best interests of the child. The attitude of the Supreme Court of Canada on spousal maintenance is obviously different from that of the United Kingdom.The Supreme Court held that a court would not easily interfere with a separation agreement between parties without establishing a causal link between the marital mutation and the resulting hardship.It can be seen that the Canadian courts will recognize the binding force of the separation or divorce agreement on the parties in terms of mutual maintenance of husband and wife.As mentioned in the discussion of prenuptial agreements, Canadian courts believe that if the life difficulties of the divorced party have nothing to do with marriage, then such responsibility should be borne by society. The letter was written in blood, though only one page.Doug still denies that the blood-stained leather jacket is his, but we have found photos, taken the day before Shirley disappeared. In fact, Doug has nothing to excuse, except to say, "I didn't do anything." That's what every prisoner would say, and it's really interesting.Criminals are criminals, they are always blaming others for wronging them, always blaming others for their problems.When have you ever seen a criminal walk into a courtroom by himself and say "I did this"?At least I have never met. It doesn't help that Doug has gone to great lengths to cover up his crime.It never occurred to him that the cat he petted before the murder became his confidant, the cat he liked-Snowball.The difference between Xueqiu and Xueli is just a word, one has been killed, and the other has avenged Xueli.Doug regrets perhaps a little.He may not know cats as animals until now.Snowball was born of "Adam and Eve" in the cat family. It may have been produced in this ancient population, and it also underwent a great intercontinental migration. A third of offenders own cats and a quarter of offenders own dogs.If you leave a DNA trace at a crime scene, like your name, address, and social security number, those are very useful.If the parties cannot be found, we can also find them by relying on the pets left behind or clues about pets.This happened to Doug Benmins when his pet Snowball turned him in. Doug was brought to justice when he was jailed for 18 years for Shirley's murder. The case became an important case in the history of forensic science because it was the first time that animal DNA was used to convict a killer. Since then, my life has also changed, which surprised me.Ever since the Snowball case became well known in the forensic community, every two weeks I have received a call from the police who were investigating a crime and found animal hair at the scene, asking me to help. Eliot highlighted the following two lines in his famous collection of poems "The Book of Old Cats Who Are Good at Dressing Up": "You have now seen clearly how different cats are from people like you and me. Alike." And now we've learned to use their DNA.Faced with this situation, Doug Benmins could only look up to the sky and sigh!By the way, in the photo he is wearing the same leather jacket found at the crime scene. In homicide cases, the head of the deceased is often the main target of criminals.Skull fractures occur when mechanical forces exceed the elastic resistance of the skull.Fractures can be divided into linear fractures, depressed fractures, hole fractures and comminuted fractures.Linear fractures of the skull may have linear cracks, and the skull is broken, but there is no depression or significant displacement of the local bone, the cracks are also small, and the fractures are mostly formed by small blunt round injuries.Assuming that the blunt force blow caused by the collapse of the skull bone is damaged, it is a depressed fracture.In the deepest part of the depression, it can often be seen that it is consistent with the most protruding part of the contact surface of the blunt instrument. This kind of fracture is generally formed by irregular edges and corners or a spherical blunt instrument under the impact of large mechanical force and fast speed. .At the same time, severe blunt force blows are also likely to cause the victim's hedging craniocerebral injury.