Erik Ablin, a Justice Department spokesman, confirmed the plan, which hasn't been publicly disclosed, and said details are expected to be completed soon.
Proponents of the plan, including U.S. Sen. Jon Kyl, R-Ariz., and Maricopa County, Ariz., Sheriff Joe Arpaio, say taking DNA from federal detainees would solve many crimes committed by illegal immigrants and make it easier to identify and track potential terrorists.
Opponents, such as Caroline Fredrickson, director of the American Civil Liberties Union's Washington office, say such mass seizures of DNA violate privacy and do little to improve law enforcement.
Fredrickson says the law that defines federal detainees is so broad that it could apply to hikers stopped by park rangers or airline passengers selected for screening. Authorization for taking the DNA was included in a bill reauthorizing the Violence Against Women Act that President Bush signed last year.
The DNA samples, which contain an individual's unique genetic code, would be compared against genetic profiles from 3.9 million criminals and 157,000 unsolved crimes held by the system of federal and state DNA databases that the FBI administers. The FBI says its system has aided more than 41,000 criminal investigations since 1990.
DNA from federal arrestees and detainees would be held on a computer index, enabling law enforcement to track illegal immigrants who return after being expelled from the USA or who commit crimes after being released. War-on-terrorism detainees, who often use aliases, could be positively identified by DNA and linked to evidence seized at suspected terrorist sites.
"We know from real-life examples that a database of arrestees can prevent many future offenses," Kyl said in a statement.
The plan would greatly increase the pool of DNA profiles available to law enforcement. In most states, a person must be convicted of a crime before his DNA is added to the national system, which the FBI calls CODIS. In seven states, DNA can be taken from suspects after they are arrested and formally charged.
The new plan would apply to "any person arrested under federal authority and from any non-U.S. person who is detained," according to the Violence Against Women law. Each year, the greatest number of those are illegal immigrants caught at the border or rounded up after entering the country.
DNA from immigration violators would remain on file permanently. Genetic profiles from people arrested for federal crimes could be removed from the database if they are not convicted.
Law enforcement authorities say illegal immigrants commit crimes out of proportion to their numbers. A Justice Department study of 100 illegal immigrants arrested and released by local authorities in 2004 found that 73 were later rearrested. "To me, it's a no-brainer," Arpaio says. "Regardless of how you feel (about illegal immigration), nobody wants criminals to get a free pass to come in here." Fredrickson says collecting DNA from anyone detained by a federal officer would clog the system to "where it becomes useless."