Convicted felons in Virginia must give blood samples for a statewide DNA data bank beginning this month under a new law designed to give police more sophisticated crime-fighting tools.

The DNA data bank, which could be the first of its kind in the country and will store characteristics unique to an individual's blood in a computer in Richmond, is expected to be up and running early next year.

Virginia was the first state to implement DNA testing, and last year, under a measure signed by then-Gov. Gerald L. Baliles, the state began collecting blood samples for the data bank from state prison inmates convicted of sex offenses. The law was expanded this year to include all convicted felons in the state, regardless of their crime.

DNA, or deoxyribonucleic acid, is the basic genetic material found in cells of every living organism. By analyzing the DNA of semen, tissue, blood or hair left at crime scenes, investigators can establish whether an individual was at the scene. Scientists believe that each person's DNA is unique, and that a person's DNA does not change over time. Much like computerized fingerprinting, DNA gives investigators a powerful and timesaving tool.

"The potential is almost unforeseeable," said Peter M. Marone, assistant director of the Division of Forensic Science in Richmond. "The key to the whole thing is going to be getting the samples in the first place."

Last week, health-care workers at the Fairfax County Adult Detention Center dispensary began drawing blood from felons before they were released from the jail. Workers are also taking blood samples from felons who are placed on probation and who have been ordered by circuit court judges to give samples, according to Fairfax Sheriff Carl Peed.

Test tubes containing the blood are shipped to the Division of Forensic Science in Richmond, which will receive about 15,000 samples a year from across the state, said Marone, who is overseeing the data bank. The state is in the process of obtaining equipment and training employees for a lab in Richmond that will become the DNA data bank, he said.

"The compilation of a DNA data bank might very well lead to more rapid identification of perpetrators," said Warren Carmichael, a spokesman for the Fairfax County police department.

Although law enforcement officials are embracing their latest crime-fighting tool, actually putting the data bank together may be no easy feat. In particular, implementing the new law may be difficult for rural jails that, unlike Fairfax County, do not have their own health-care staff. "That's one of the problems we are working on now," said Marone. "It becomes a knotty problem {of} who draws the samples."

Although it may be too early to tell, the new law may cause logistical problems, Peed said. For example, felons with multiple offenses may be needlessly tested more than once as they are moved around various jurisdictions.

"It could be quite burdensome," Peed said. "We are very fortunate here in Fairfax County, but some of the more rural jurisdictions may have some trouble complying with this law."

The FBI began accepting DNA cases in 1988, when the bureau opened a DNA laboratory at its headquarters in Washington.

Like Virginia, several other states are in the process of establishing DNA data banks, said James Kearney, an official with the FBI's Forensic Science Research and Training Center in Quantico. Eventually, the FBI hopes to set up a clearinghouse so states can share information about criminals who commit crimes in other states, he said.

"As far as its potential use in law enforcement, it's an extremely valuable data base not only to solve unsolved crimes but to locate someone like a Ted Bundy," Kearney said.