Around 1 a.m. on a Thursday morning last November, Sarasota, Fla., police detectives rousted air-conditioning repairman Mark A. Daigle from his sleep, arrested him in connection with a series of four vicious rapes and began searching his home in southern Manatee County for evidence.
Law enforcement officials, however, already had the evidence they needed to find Daigle - his own DNA, police said.Using semen from one of the crime scenes, Florida authorities identified the DNA, the unique genetic building block of a human cell, but it didn't match anyone in the Florida criminal DNA data-base. Alarmed over the rapist's violence, which included breaking into homes and beating and tying up his victims, police asked the two other southeast states with DNA databases - Virginia and Georgia - to check their files.
"We knew this guy was going to strike again," said Lt. Jim Schultz, head of Sarasota's detective division.
A day after receiving the information, Virginia's state forensic science laboratory called Florida with a Social Security number and a name: Daigle, who had been arrested and imprisoned in Virginia for burglary.
Dr. Paul B. Ferrara, director of Virginia's laboratory, said Daigle's case "clearly demonstrates the (potential) power of a national DNA databank."
That's exactly what the FBI is helping to build with a pilot network among eight states - California, Florida, Illinois, Minnesota, North Carolina, Oregon, Utah and Virginia. - that started up last month and by the end of this year is expected to link all 50 states. Instead of calling to ask to search Virginia's database and faxing information, Florida officials now can tap right in by computer.
"You just send your data up and it's searched automatically," said David Coffman, DNA database administrator for the Florida Department of Law Enforcement.
Police agencies began using DNA identification less than a decade ago, but the science has progressed rapidly and, as of last summer, had been used in more than 6,800 cases, including the O.J. Simpson trial, according to the FBI. Each person's DNA pattern is unique, making it an extremely useful tool for identification.
DNA analysis is only applicable in a crime where the attacker left body fluid, such as blood or saliva. Still, the burgeoning science has linked a convicted criminal, whose DNA was filed in a database, to a crime scene in 118 cases and matched evidence from different crime scenes in 143 cases, FBI officials said.
Police can use the technology, not only to find a criminal, but to rule out an innocent suspect. FBI Director Louis Freeh said 25 percent of the suspects whose DNA is brought to the bureau's laboratory for testing are exonerated.
Even now, however, many states have barely started building a DNA database and, until recently, police mostly were comparing DNA from a crime only with their state's database. It was a cumbersome and time-consuming process to check another state's files.
The FBI plans to improve all that. Congress appropriated money allowing the bureau to offer to help any state set up the equipment and train the people to complete a database and link to a national network.
"This is an exciting technology, and it works. But the infrastructure in the U.S. needs to grow," said Steve Niezgoda, a DNA program manager at the FBI. "We're working 15,000 out of a quarter-million rapes in the U.S."
To build a database, states take blood samples from some convicted criminals, analyze the DNA and store it in a computer file. That's an expensive process, and only 80 laboratories in 36 states currently do it.
Nationally, states have collected more than 450,000 samples but analyzed fewer than a third of them. Virginia, for example, has collected 160,000 samples but only analyzed and filed 10,600. Many states have barely started taking samples.
Further complicating the process, while 48 states have passed laws requiring samples from convicted criminals, the states vary on which ones. Virginia collects from all felons. Florida takes a blood sample only from people convicted of sexual assault, lewd and lascivious conduct, homicide, attempted homicide, aggravated battery, carjacking and home invasion robbery.
If Daigle's burglary conviction were in Florida, he wouldn't have been on file.
"We're missing a lot of people," Florida's Coffman said.
FBI officials expect that, as the cost drops, most states eventually will collect from all felons. As with many scientific advancements, DNA analysis has raised ethical concerns. Conceivably the technology could be used, not for identification, but to see if certain kinds of people have a genetic predisposition toward criminal behavior.
Dr. Phil Reilly, a geneticist and lawyer who heads the Shriver Center for Mental Retardation in Boston, said he supports the use of DNA analysis for identification but said the science must be watched.
"Is this a new technology in law enforcement that can be used fairly, that promotes justice, reduces crime and protects the innocent?" Reilly asked.