Thursday, August 22, 2002

When bones were found in Rock Creek Park a few months ago, detectives had several questions. Among them: Were the bones human? If they were, to whom did they belong, and how did that person die? The bones didn’t remain a mystery for long. After involving forensic scientists, it was determined that the remains were human and belonged to Chandra Levy, the intern who had been missing for more than a year.
Miss Levy’s disappearance and the O.J. Simpson murder trial are examples of cases that have helped put forensic science on the mental map of millions. Current TV shows, including “CSI Crime Scene Investigation,” “Crossing Jordan” and “Law & Order,” have added to the public’s interest.
This fascination might be new for most Americans, but for Douglas Ubelaker, a forensic anthropologist and curator of anthropology at the Smithsonian Institution’s National Museum of Natural History, forensic science has been a job and a passion for close to 40 years.
“I got intrigued by what you can learn about someone from their bones,” Mr. Ubelaker says. “You let the remains tell the story.”
A skeleton can tell a scientist not only about the death, but also about the life of the deceased. On a recent morning, Mr. Ubelaker displayed a skeleton in the Smithsonian’s collection. It belonged to a homeless man who had died under a bridge, but judging from the teeth, which had fillings, the man had not always been down and out.
Mr. Ubelaker’s specialty is just one of several in forensics, including toxicology (the study of harmful effects of chemicals or drugs); forensic pathology (the study of disease, which includes such procedures as autopsies); and criminalistics (the interpretation of a wide range of physical evidence), which is the largest section of forensics.
A forensic scientist is charged with interpreting evidence, not solving a crime. He or she may be a witness for either prosecution or defense in a court case. Mr. Ubelaker works almost exclusively with the FBI and has done so for more than 25 years. He works on about 30 cases a year. This year, his forensic work included the Levy materials, on which he won’t comment.
A normal case goes something like this: The FBI might send him a bone and a report on where and how it was found. It is Mr. Ubelaker’s assignment to figure out such things as sex, ancestry (race), age and possible evidence of foul play.
First, he determines whether it’s a human or animal bone.
“I can often tell if it’s a dog or cow bone in a matter of minutes, sometimes seconds,” Mr. Ubelaker says.
Usually, the shape and size of the bone give it away, but if it’s a bone chip, the query gets more complicated. Sometimes, the forensic scientist will cut out a section of the bone and put it under the microscope.
The way the bone has formed over the years tells the story. A cross section of a bone looks much like one of a tree trunk, with rings marking the passing years. In bone, however, besides the rings, there also are circles, called osteons. If the osteons are layered neatly, one next to the other, the bone is likely that of a dog or other animal.
In humans, the osteons are more randomly distributed.

If Mr. Ubelaker determines that the bone belonged to a dog, the FBI usually won’t pursue it further, but if it belonged to a human, that’s a different story. Mr. Ubelaker’s next step will be to determine the age, sex and ancestry, a term anthropologists use instead of race.
If the evidence submitted is a “complete bone,” rather than a fragment, Mr. Ubelaker can determine the age by looking at such things as the ends of the bone. If they are fused, the bone belonged to an adult. If they show signs of arthritis, they may have belonged to an older adult. A child’s bones are smaller, and the ends are not fused (they look more sprouty, less rounded).
Sex often can be determined by the size of the particular bone, and ancestry often can be determined by the shape of the bones. Black people, for example, often have relatively straight upper leg bones.
If Mr. Ubelaker has a difficult time making a determination about a certain bone just by looking at it and needs something with which to compare it, he has more than 30,000 sets of bones at his disposal at the Smithsonian.
“The Smithsonian is one of the world’s meccas for human skeletons,” Mr. Ubelaker says.
It is becoming increasingly common, he says, for him to receive bone fragments as opposed to complete bones. “They are so small I don’t know if it’s even bone,” he says. “It could be drywall.”
In those cases, he might put the evidence under the microscope to determine if it has bone-building features, such as osteons. Or he might have it analyzed in a new type of scanning microscope that helps identify materials.
One of the best weapons forensic scientists have is DNA, but the procedure of extracting and analyzing DNA is time-consuming and costly, which is why the FBI sends the bones or bone fragments to Mr. Ubelaker or other scientists to make a preliminary determination. If it’s dog bone or drywall, it’s hardly worth conducting a DNA analysis.

While the techniques of forensic science whether forensic anthropology or forensic pathology keep getting better and better, crimes can’t be solved if the evidence is compromised, which was what O.J. Simpson attorney Johnnie Cochran claimed the Los Angeles Police Department had done.
“A lot has happened since O.J. Simpson,” says Dr. Michael Baden, a New York forensic pathologist and author of “Dead Reckoning: The New Science of Catching Killers.”
“Law enforcement has realized they have to learn about protecting the crime scene,” Dr. Baden says. “There is a great new interest among law enforcement to learn about forensic science, which is very encouraging.”
He says that as criminals learn more about how to avoid giving evidence, law enforcement has to respond by becoming more vigilant in keeping crime scenes clean and uncompromised. More and more rapists, for example, will use a condom to avoid giving away DNA.
“The bad guys also read the newspaper, and they also are aware and able to try and avoid giving over forensic evidence to investigators,” Dr. Baden says.
However, they often throw away the condom in the trash or in bushes just feet away from the crime scene, which means DNA can be extracted from the condom.
“The most important person at the crime scene is the first officer, who is usually the least experienced,” Dr. Baden says. “You need to establish a big perimeter and make sure the scene isn’t contaminated.”
Not only law enforcement is showing interest in learning more about forensic science. Both public schools and universities have seen a surge of students interested in taking classes in forensics.
The American Academy of Forensic Sciences, based in Colorado Springs, has received about 1,000 requests in the past year from teachers across the nation who want to add forensics to their science curriculum.
“It’s very encouraging because everyone benefits from learning more about forensics,” says Jim Hurley, director of development at the academy, “and it keeps kids interested in science.”
At George Washington University, at least 400 students fight for the 80 slots available each year in the Department of Forensic Sciences, says Moses Schanfield, professor of forensics and chairman of the department.

While TV shows have created a buzz about forensics, the portrayal of the role and capability of the forensic scientist is often warped, Mr. Schanfield says.
“‘CSI’ has unlimited money,” he says. “The reality is that a crime lab can’t do it all because they don’t have the equipment or the resources. You don’t do a DNA analysis overnight.”
Also, the shows portray the scientist and the detective as one and the same, which is far from the truth.
“The big myth perpetuated by TV is portraying us as too much involved with whodunit. Our role is to determine what happened,” Dr. Baden says. “The science should be independent of whodunit.”
It’s simply not the scientist’s job to solve the crime.
Mr. Ubelaker sometimes avoids information surrounding the case because he wants to keep his mind clear and his opinions objective when first looking at a bone.
“You need to know what the problem is, and what it is [the FBI] wants to know but mentally I try to remain detached,” he says.
One case in particular showed how important it is to maintain detachment from everyone else’s conclusions and assumptions, Mr. Ubelaker says.
Several years ago, he received a bone from a campground in Alaska. It had a steel plate attached to it, which indicated an orthopedic procedure. So, the bone was human, right? Only humans would have such an elaborate procedure or a much loved dog. After further research, it turned out to be a dog bone. Case closed.
“I think that’s a good example of how important it is to keep an open mind,” Mr. Ubelaker says.

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