A forensic research laboratory at the Wrocław Medical University in southwestern Poland is on track to becoming a European leader in forensic genetics. The science, also known as serology, or hemogenetics, makes it possible to establish paternity, expose murderers and check the authenticity of religious relics.

Who's the father?
Paternity testing as a scientific method began with an early 20th-century discovery by Polish genetic researcher Ludwik Hirszfeld, who combined serology with genetics. In 1910, he proved that blood types, discovered just 10 years earlier, followed Mendel's laws of heredity.

However, Hirszfeld made one mistake in his research: he examined blood types in families he knew and trusted their declarations about who was whose father. In 1924, German mathematician Felix Bernstein gave a new impetus to the development of serology, and Prof. Fritz Shiff from Berlin made a breakthrough step by carrying out the world's first serological examination in order to solve a paternity dispute.

Poland's first documented paternity test was conducted by Prof. Jan Olbrycht from Cracow in 1926. Before World War II, Polish serologists determined paternity during tests that made it possible to exclude some 25-30 percent of suspected fathers. After World War II, the science developed rapidly. Prof. Bolesław Popielski, who previously worked with Hirszfeld, led the development of forensic medicine in Wrocław after the war, drafting legal regulations concerning paternity testing in Poland. By the 1980s, the world's leading laboratories, including those in Poland, learned to exclude 95 percent of suspected fathers.

A true breakthrough came in 1985 when British researcher Sir Alec Jeffreys conducted the world's first DNA paternity test. With this method, paternity can be established with almost 100-percent certainty.

In Poland, the first examination involving the use of DNA tests in a court case was made in 1989 by Prof. Ryszard Słomski from Poznań. He carried out the test in Göttingen, Germany, and soon brought the method to Poland.

The DNA testing technique was also applied at the Wrocław Medical University, which in 1990 delivered its first expert testimony in court. By 1991, the method was used by three forensic medicine institutes in Poland: in Poznań, Wrocław and Lublin.

Nothing is certain
While at first laboratories using DNA tests issued clear verdicts that someone was or was not the father, today researchers are more cautious. They usually limit themselves to stating that a person's paternity is "highly probable, to the point of certainty."

This is due to two test errors, says Prof. Tadeusz Dobosz, head of the Molecular Techniques Unit of the Forensic Medicine Department of the Wrocław Medical University. "The first error was made in a Scottish village where a woman filed a paternity suit against two of her neighbors with whom she had sexual relations. DNA tests showed that both men matched the child's genetic profile. The village was visited by a number of geneticians, who also tested other residents, and it turned out that at least several other men could have fathered the child. This resulted from the fact that all the residents were genetically similar, like laboratory mice, because no one had been leaving the village for ages and there were no newcomers."

The other error occurred in Poland. A woman sued a man for paternity, but admitted that she had also had intimate contacts with the man's brother. The judge summoned the other man as a witness. Both men had their DNA tested and it turned out that both could have fathered the child. Normally, the likelihood of two people having numerous identical chromosome pairs is extremely low; yet this is exactly what happened.

After these two cases were described in medical literature, geneticians around the world withdrew from making clear-cut judgments and tightened the criteria. Now, the standard practice is that paternity is considered confirmed if it is at least 99.9999 percent certain. Testing has to be carried out until at least four nines after the decimal point are obtained. Such a result means that the probability of error is one in a million samples.

Around 3,000 paternity tests are carried out in Poland annually, according to data from the country's 10 forensic medicine institutes at medical universities and the Institute of Forensic Research in Cracow. However, experts say that the overall number of tests carried out nationwide is larger because they are also performed by private laboratories that apply less strict procedures and criteria.

Depending on the technique, testing in a certified laboratory takes from one to three weeks. The most widely used method is a multiplex technique using genetic analyzers.

Too much information
The forensic medicine laboratory at the Wrocław Medical University was the first lab in Poland to carry out a prenatal test in order to determine paternity. The test, conducted in 2000, involved a pregnant woman who had been raped. Under Polish law, a woman has the right to have an abortion if the pregnancy is the result of rape. However, the test excluded the rapist's paternity and the woman did not have an abortion.

"Paternity tests result in important decisions for people, so we often deal with an excess of information," says Dobosz. "We sometimes learn things that we would rather not know, and moral dilemmas appear. For example, in one case, tests pointed to a 14-year-old boy as the father, while sexual relations with someone under the age of 15 are a crime. Some other tests revealed that the child of a young woman had been fathered by the woman's father. The truth would have never seen the light of day had it not been for DNA testing."

Sometimes, though extremely rarely, scientists must also establish maternity-for example, when babies get switched in a hospital by mistake or when families reunite after a long time. Maternity testing is also applied during the identification of dead bodies, when the dead person's DNA is compared with the DNA of their mother.

Blood, sperm and tears
Another important role of forensic genetics is the examination of physical evidence. Mostly, this involves examining human or animal bloodstains, including menstruation or postpartum blood that has a different biochemical composition. Polish researchers have many achievements to their credit in this field.

The first Polish researcher to develop a test for distinguishing bloodstains from other types of stains was Prof. Ludwik Teichman from Cracow in the mid-19th century.

Another Polish researcher who contributed to the development of forensic genetics was Edward Piotrowski, who worked in Vienna in the 19th century. He carried out experiments on rabbits in order to retrace the development of events at the crime scene. Examining the shapes of bloodstains and the way blood is splattered is useful for police investigators in determining the course of a crime. Blood from the lungs or from the nose leaves different stains, and they also look different depending on whether the victim was standing or lying down.

The Wrocław laboratory also specializes in difficult cases linked with sperm examination. "The problem is that we usually deal with a mixture of sperm and secretions from the victim's body," says Dobosz. "So first we have to establish which part of the genetic profile of the sample belongs to whom, and that can be extremely tedious work. We try to isolate the perpetrator's genetic material from the mixture."

Roughly, there are two ways to do that. In the traditional method, in order to isolate the perpetrator's genetic material (sperm cells), it is necessary to remove the material from the epitheliums. The material must be dissolved carefully so that only sperm cells remain in the sample. The other, better method, examines the features of the male chromosome when a woman is the victim. The Wrocław laboratory applies both methods, so it handles the most difficult cases nationwide.

Bones of saints, hair of criminals
The Wrocław laboratory is a pioneer in the non-destructive isolation of DNA from bones, specifically teeth. Until recently, in order to examine the DNA of a tooth, the tooth had to be pulverized, which means destroyed. But if you send a tooth to the Wrocław laboratory, you will get it back, and, what's more, it will return cleaner and whiter. How is that possible? "This is our professional secret," says Dobosz. Owing to this method, the lab obtains orders from museums and religious organizations, for example, to examine the authenticity of "holy relics."

Details related to such examinations are secret, since faith is a sensitive issue, Dobosz says. To date, the laboratory has examined the remains of the Blessed Czesław, the patron "saint" of Wrocław. The laboratory is making efforts to obtain the sacral bone of Polish 19th-century poet Adam Mickiewicz and a sample of the heart of Romantic composer Frederic Chopin-to determine whether or not Mickiewicz died of cholera or, perhaps, was poisoned, as some suspect, and whether Chopin suffered from tuberculosis, asthma or cystic fibrosis.

The institute also handles a new type of orders for the examination of tissue after cancer surgery. Most of these include material from mastectomy. The patients want to make sure their breast removal was justified-that they really suffered from cancer. Dobosz says in several cases these doubts turned out to be justified, providing grounds for compensation claims.

The genetic examination of tissues helps determine those responsible for sex crimes, road accidents and other acts. Sometimes a single hair is enough to prove someone's involvement in a crime. Without the latest achievements in genetics, it would be impossible to precisely identify babies switched at birth, dead persons, or blood samples switched deliberately by people stopped for drunk driving.

Precision is key
The future of forensic genetics lies in even greater precision, Dobosz says. When he started to work in this field, Dobosz needed a bloodstain the size of a saucer in order to determine someone's DNA profile. A few years later, a trace of saliva on a postage stamp was sufficient; now all Dobosz needs is the tiny fragment of tissue that sticks onto the bullet that pierces a victim's body.

But there is always room for progress. "Perhaps we will see more effective examinations of DNA destroyed by UV rays and decomposing processes, for example," Dobosz says. "Today we can examine samples that include DNA fragments with 100-300 pairs of nucleotides. In the future, we will probably be able to analyze much more degraded material."

This fall, the Wrocław laboratory will be equipped with a state-of-the-art robot that can isolate and test hundreds of samples at the same time. The institute will then be the only center in Central Europe capable of carrying out mass examinations, including the identification of hundreds of dead bodies within a short time. Among other institutions, such equipment is currently at the disposal of Britain's Scotland Yard, which used it after the July 2005 attacks in the London Underground.

Alicja Giedroyć