In a computer at a secret location, the FBI will open a national DNA data base tomorrow that advocates say could significantly reduce rape and other crimes by helping to catch repeat offenders earlier.

The data base, with a new generation of forensic DNA techniques, promises to be so efficient that some civil libertarians fear it will be expanded from people convicted of crimes to include almost everyone, giving the government inordinate investigative powers over citizens.

The national DNA data base consists of 50 data bases run by the states but unified by common test procedures and software designed by the FBI. As of tomorrow, it will be possible to compare a DNA sample from a suspect or crime scene in one state with all others in the system.

The national data base has been nearly a decade in the making. The final pieces fell into place in June when Rhode Island became the last state to set up a DNA data base.

But the system still faces many unresolved issues, which are likely to play out according to the reaction from the public and the courts. One such issue is what types of offenders should be included. Another is whether the mass screening of suspects' DNA will prove constitutional.

DNA, the chemical that embodies a person's genetic programming, can be found almost everywhere. People shed a constant torrent of dead skin cells. Criminals leave blood when breaking and entering; they shed hair and skin cells in fights, deposit saliva on glasses and leave sweat stains in head bands. From only a few cells in such sources, enough DNA can be extracted to identify the owner.

The crime-fighting potential of DNA data bases is becoming evident from the experiences of Britain.

The data base there initially focused on sex offenses but has spread to include burglaries and car theft because of the high number of DNA matches that police forces were obtaining.

Pub Date: 10/12/98