The death toll from the tsunami disaster has been estimated to be at least 155,000, although it?s believed there may never be an accurate count of those still unidentified or missing.

Genetic profiling through DNA testing is playing an increasing role in the identification of tsunami victims as well as the conviction of criminals. But while DNA evidence can be helpful to families searching for loved ones, some people wonder if it can lead to an invasion of privacy. VOA?s Deborah Block has more on this controversial scientific tool.

In Thailand, the bodies of hundreds of victims of the tsunami disaster are being dug up so medical staff can collect DNA samples from them. So far, it's estimated that at least 5,000 people were killed, nearly half of them foreign tourists. Authorities are concerned foreigners may have been mistakenly buried as Thai nationals in the chaos following the tsunami.

Pornthip Rojanasunan is a Thai forensic expert. "We will collect the DNA from the relatives and collect the DNA from the bodies and send the samples to the United States, the Utah University, to match the DNA. If the DNA is confirmed, we will release the body in five days," she said.

While DNA testing brings closure for some people, it opens a door of uncertainty for others. Here, in the small U.S. town of Truro, Massachusetts, every man in town -- 790 of them -- is being asked, but not forced, to give a DNA sample. Investigators hope it will help solve a three-year-old murder case of a woman fashion writer.

Many residents are cooperating, but others see the move as a serious invasion of privacy. James Stewart, a resident of Truro says, "I would like to see the murderer be found, but to invade everybody's privacy in the town is just a bit ridiculous, if you know what I mean, and I feel as an American citizen it is just wrong."

Kevin McElfresh is head of Bode Technology, near Washington, DC, which does DNA testing for criminal cases. Mr. McElfresh says, "The real beauty of DNA testing is that you have a solid, real piece of information that says that this person is tied to this crime with certainty. All DNA does is say we know who this person is. It's up to a jury to decide that person is a criminal."

While DNA testing has helped put some people in prison, it has gotten others released. Larry Johnson, who spent 18 years behind bars for a rape he says he didn't commit, was released after being cleared by a DNA test. DNA technology wasn't available at the time of his trial.

DNA is a molecule found in a cell, which contains a person's genetic blueprint, and everyone's is different. DNA can be taken from just about anything including fingerprints, blood, bones, or saliva. It can even be lifted from evidence that is decades old. The Federal Bureau of Investigation, the FBI, has a national data bank containing thousands of DNA profiles from criminal offenders.

Sarah Hart is head of the U.S. Justice Department's "National Institute for Justice." It provides support to DNA criminal programs. She says, "I think what you are going to see that DNA is for this century, what fingerprints were for last century. It is an incredibly powerful tool and one we need to invest in."

U.S. states also have DNA criminal data banks. But states like Virginia are going one step further, not only taking DNA from convicted felons, but also requiring samples from suspects arrested for violent crimes.

Police officer to suspect: "We have to take a DNA sample." The law has raised objections from civil liberties groups like the Electronic Privacy Information Center.

Anna Slomovic, a policy analyst for the group, says the law is not fair because it can target anybody. "Some states permit DNA data to be kept indefinitely which means even people who are completely innocent who have no connection to a crime, gave their DNA voluntarily, for example, as witnesses or bystanders, or for some other purposes of elimination, could conceivably have their DNA in a government databank forever," she said.

She is concerned that information in a person's DNA profile could hurt them in the future. Although doubting that will happen, she says, "It's a unique identifier but it tells you nothing about the person's physical characteristics. It tells you nothing about medical information. It's much less intrusive information than information that you routinely see on perhaps on a driver's license. Some databases, especially the FBI database, store limited information. But even that limited information can be used to deduce paternity for example. That is not something that's on your driver's license."

Kevin McElfresh, of Bode Technology, says laws are in place to prohibit DNA samples from being used for biological research. But Anna Slomovic says more laws need to be passed to protect the privacy of DNA criminal profiles. "Abuses are always a danger with any database. There is always a possibility that someone will steal the contents of the database," she said.

But Sarah Hart of the Justice Department says the profiles are secure. And with the growing use of DNA testing, the technology apparently is here to stay.