It was a barren crime scene that first faced investigators at the Lowry Hill, Minneapolis, apartment where a woman was sexually abused and strangled to death on Nov. 17, 1991.  No fingerprints were raised. No footprints were found. There were virtually no leads for police to follow.

But despite the absence of these tried-and-true forms of physical evidence, the killing would eventually spur a milestone in the use of another, relatively new form of evidence: DNA. 

Whoever killed the 23-year-old secretary had left behind enough genetic evidence to raise a DNA profile. Matched against a database of known profiles, the sample snared a suspect.  The "cold hit" fingered convicted rapist Martin Perez, who was later found guilty of the murder and sentenced to life in prison without parole.

It was the first case in the nation cracked solely on a cold hit — when DNA from a crime and a database match up with no other known evidence linking the two. Now, as the 50th anniversary of the discovery of DNA is celebrated, the federal government wants to dramatically broaden the federal database to include DNA from juvenile offenders and adults who have been arrested, but not necessarily convicted.   

Current federal law only allows DNA from convicted adults to be placed in the database, which now has about 1.3 million profiles.

While boosting the size of the database could help police solve more crimes, civil liberties experts are worried that the libraries of DNA could signal the further erosion of personal privacy.

Database detectives

Cold hits have become routine within many law enforcement agencies.

DNA profiles extracted from crime scene evidence — such as semen, saliva, sweat, hair or blood — are matched against profiles of individuals stored in an offender index.  A match can give investigators ammunition for not only the interrogation room, but also the courtroom.

Click here for an interactive explanation of DNA testing

Since the mid-1980s DNA has been used to positively identify or exclude suspects during investigations and prosecutions. State laws vary on which offenders can be added to each state's database. But a trend has developed of opening the databases to a broader range of crimes. Anecdotal evidence from the last few months suggests the power these databases give investigators.

• In Virginia, a suspect linked to a 1994 slaying through a cold hit two years ago was indicted on first-degree murder charges; 
• Louisiana police recently notched their first out-of-state cold hit when authorities linked an inmate at a state penitentiary to an unsolved 1987 rape-murder in Texas;
• A Washington state man was charged in the 1999 kidnapping and rape of a 14-year-old girl abducted from her school bus stop after a cold hit linked the convicted felon to the attack;
• And in El Dorado County, Calif., investigators reported a break in a 1971 murder after DNA from the crime scene was linked to the DNA profile of an inmate in a California prison. It is believed to be the oldest case in the state reexamined as a result of a cold hit.

"We are seeing an influx of old cases being solved and we are just scratching the surface now," said Manuel Valencia, a spokesman for the California attorney general's office, which oversees the state's DNA database. The database scored 140 cold hits last year.  "Investigators are solving cases previously thought unsolvable."

Forming a digital dragnet

Back in 1991, the DNA profile taken from the crime scene in the Perez case could have lingered anonymously in a lab with other evidence from unsolved crimes. 

But a 1990 state law required him to submit a DNA sample to a growing database of sex offender profiles. At the time, Minnesota was one of 20 states with laws requiring sex offenders and some other prisoners to give blood samples for DNA profiling. 

Taking a DNA swab

Soon, murderers and other violent felons joined sex offenders in state DNA databases, and the genetic net being cast is growing wider each year.

Rob a home in California and your DNA profile could wind up in a database, if proposed legislation passes. The same goes for sticking up a bus driver.

In New York, shoplifting enough high-priced clothing may soon require a DNA sample even before any kind of conviction.  And in New Jersey, just committing a "crime" — an offense punishable by more than six months in prison — may land your genetic profile in a state database.

In total, 17 states expanded DNA databases last year by adding new types of offenders who must provide a sample, according to the National Conference of State Legislatures. 

States have been rolling out DNA database laws since 1989 when Virginia became the first state to launch a forensic DNA profile database.  Within nine years every state had laws requiring the collection of DNA samples from certain violent felons.

The FBI nationalized the system in 1992 with the launch of its Combined DNA Index System (CODIS), which allows federal, state and local crime laboratories to electronically exchange and compare DNA profiles.  Since the system became operational in 1998 it has continued to change the way investigators solve crimes.

"There could be a profile from someone in Michigan on the national database," said Sgt. Gary Smith, head of the Miami-Dade Police Department's cold case squad in Florida.  "We wouldn't have a clue to go after this guy in Michigan without the database." 

Critics acknowledge the benefits of the databases but question their rapid growth.

"My concern is in increasing the input into databases," said Steven Benjamin, chairman of the Forensic Evidence Committee of the National Association of Criminal Defense Lawyers.  "We are now in that gray area between taking DNA only from convicted felons and taking DNA from everyone across the board."

Advocates see the inclusion of more classes of criminals in the databases as a natural extension of the justice system at work.

"Our whole criminal justice system is built on keeping contact with people who have had contact with criminal justice," said Tim Shellberg, a partner at the law firm Smith Alling Lane, which lobbies for larger databases.

While 26 states require DNA sampling of all convicted felons, some states have already lowered the hurdle to putting someone's genetic blueprint on file. This year Virginia began collecting DNA samples from anyone arrested for a violent felony, making it the first state to begin mandatory testing so early in the legal process.

Many states require DNA sampling of all convicted felons

Last year, Texas began testing certain repeat offenders once they are indicted, a step just beyond arrest. Louisiana has similar arrestee legislation on the books, but staffing and financial concerns have kept the process on hold. 

Regardless of state laws, however, the national CODIS system currently only includes profiles of those convicted of a crime. The White House wants to open the database to a wider set of offenders, and has promised $1 billion over five years to help bolster DNA analysis in the United States, including the enormous backlog of rape kits waiting to be tested.

Some look with hope — and others with dismay — to the British DNA database as the future of the state databases and the CODIS system.

The National DNA database in England collects samples from suspects "charged, reported, cautioned or convicted" of any crime that warrants a prison term.

Supporters of the British system point to a recent case in which a DNA sample taken from a man caught urinating on the street linked him to an unsolved rape. In another recent case, DNA taken in conjunction with a drunk and disorderly charge linked a man to 1999 burglary.

Such anecdotal evidence becomes what law professor Michael Smith called a "we had him in our hands" argument for expanding the databases to include even nonviolent offenders in case they go on to commit more serious offenses. 

According to Dr. Paul Ferrara, the director of Virginia's Division of Forensic Sciences, this happens quite a bit.

"It turns out that a significant number of people who are in our database because they committed a drug offense or check fraud were later identified in a violent crime as a result of us having their sample," said Ferrara. 

In Virginia some 85% of the state's 1,079 cold hits would not have been made if the database did not include all felons, even the most nonviolent offenders, according to Ferrara. 

For advocates of the databases, expanding to certain arrestees is simply the next logical step.

Keeping profiles on file

In addition, they argue, the current arrestee collection laws provide for the destruction of the samples in the absence of a conviction so the innocent are not wrongly profiled.  Privacy advocates are not convinced. 

"How do we know if they have destroyed the sample?" said Smith, of the University of Wisconsin.  "It's a problem that is not really resolved by saying we have a law against it.  If a government with an open-ended future agenda possesses something of value but the value is undetermined at this time, to expect its destruction is tough."

Stored DNA samples

And Peter Neufeld, a New York attorney and DNA expert, points to the questionable practices of what he calls "usual suspect" databases maintained by some states.

"People arrested and not convicted, people who volunteered to give samples to eliminate themselves as suspects — the profiles are kept on file in many states," said Neufeld, a co-founder of the Innocence Project, which uses DNA evidence to exonerate the wrongfully convicted.  "All this is being done without any legislation."

Such collections are sometimes the result of DNA dragnets, like the sweep recently conducted in the search for a Louisiana serial killer.  Police swabbed the cheeks of some 800 men, many of whom own or have access to white pickup trucks similar to the one that several eyewitnesses placed at the scene of two of the unsolved crimes.

At least one participant in the Louisiana collection is threatening to sue to get his profile removed, claiming he was coerced into the voluntary collection process.

In Ohio a recent investigation by the Cincinnati Enquirer revealed that a state DNA database retained more than 1,000 DNA profiles of people after they were excluded as suspects in crimes, allegedly unbeknownst to many donors. 

Ohio attorney general spokesperson Kim Norris said that retaining the samples in the database is well within Ohio law.

"These are potential suspects, not just anyone off the street," she added.  "They are people involved in casework and crime scenes."

Laws extending DNA profiling to arrestees and beyond may also exacerbate problems of inequality in the justice system, said Smith, who drew a parallel to the problem of racial profiling during traffic stops.

"Are we going to allow individual police officers to decide whose DNA to take?" he said.  "We have a lot of evidence of the problematic results of those discretionary tactics.  It looks like an invitation to subconscious abuses."

To the list of concerns Neufeld adds the possibility of "pretext arrests" where police "can arrest you so they have an excuse to get a sample."

To iron out some of the legal and ethical wrinkles posed by the selective collection of DNA, some have suggested universal genetic profiling at birth.  Prof. James Watson, one of the Nobel Prize-winning co-discoverers of DNA, supports such a move.

"The sacrifice of this particular form of anonymity does not seem an unreasonable price to pay, provided the laws see to a strict and judicious control over access to public data," Watson told British newspaper The Independent.  "If you want to make the criminal justice system more fair, what's wrong with it?"

Privacy advocates argue that such a plan puts far too much personal information in government hands.  They contend that DNA profiles, commonly referred to as "genetic fingerprints," contain health and hereditary information not revealed by their ink splotch predecessors. 

"The amount of health related information you can get from a genetic sample is enormous," said Peter Shorett of the nonprofit Council for Responsible Genetics.  "A DNA database that is not sufficiently secure and does not have proper firewalls could really create serious problems."

DNA experts have dismissed such concerns as a misunderstanding of the profiling process in which little more than a mathematical sequence — the genetic fingerprint — is extracted from the actual tissue sample, which could be far more revealing.

Scientists argue that the small section of DNA used for profiling is often referred to as "junk DNA" because it does not contain vital health or hereditary information that could be extracted from other sections of the DNA.

"I can give you my entire DNA profile and you could glean less information about me than from my social security number," said Ferrara, who admits that the "junk DNA" may contain vital information that scientists may not have discovered yet.

DNA as viewed under a microscope

It is the fate of the original tissue samples that concern privacy advocates most. By law, most labs are required to keep the samples after the limited profile is extracted and electronically stored. This intricate point propels much of the current privacy debate.

"They are not just taking a DNA code from you," said Philip Bereano, chairman of the ACLU Committee on Databases and Liberty and a University of Washington professor of Technology and Public Policy. "They are taking a tissue sample which tells vast amounts of information about you.  The solving of a heinous crime does not justify the violation of civil liberties."

Despite the high-tech nature and vast biological possibilities of analyzing DNA, supporters of increased databases continue to liken the DNA profiles to other highly personal means of identification routinely taken — and kept — by law enforcement.

"You give a fingerprint when you are arrested and your fingerprint does not go away. Your mugshot does not go away," said Shellberg, of Smith Alling Lane.  "Why should keeping the mathematical profile on code be any different than keeping your fingerprint on file?"

The life code

So far, constitutional challenges to the increasing collection and storage of DNA profiles have been unsuccessful.  Attorneys are split on whether arrestee legislation like Virginia's will be successfully challenged.

In addition, immense backlogs and financial shortfalls in many states are likely to hold up the growth of databases no matter what laws are passed.  Many advocates for expanded databases concede that it is probably more efficient to draw the line at all convicted felons for now.

Even as some legal questions and money problems begin to fade, the ethical debate is likely to continue.

"What is important for the public to decide is, 'Do we want the government to have our life code, the code that makes us as who we are?'" said Benjamin, of the National Association of Criminal Defense Lawyers.

Adds Bereano, "People will say, 'But it solves crimes.'  If we allowed the police to randomly break into people's residences they would find huge amounts of crime that go undetected.  Solving crime is not the only public value we have in this society."

But the privacy debate over DNA databases may be just a footnote to larger questions posed by the growing ability to read and interpret people's genetic codes.

"The forensic DNA databases, which are the most regulated by law, represent an extremely miniscule risk to anyone's privacy," said Dr. Ferrara.  "What the public needs to be concerned about are all the DNA samples we leave every place we go."

In fact, the mouse you may be clicking, the keyboard you might be tapping on and the phone receiver you might be cradling all carry enough DNA for a complete genetic profile.

Courttv.com reporter Matt Bean contributed to this report.