On the back of Jayann Sepich's business card is her DNA profile, a reminder of the potential and pitfalls of technology at the heart of a privacy dispute now before the U.S. Supreme Court.

At issue is the constitutionality of a controversial state genetic testing law. Maryland's DNA Collection Act permits police to collect genetic material without a warrant from those who have been arrested, but not yet convicted of crimes. Some states allow testing for certain misdemeanors too, including sex-based offenses.

Sepich founded the group DNASaves.org after the murder of her 22-year-old daughter, a shocking crime unrelated to the current high court appeal. Her killer was not identified until three years later, after the man was convicted of a separate armed burglary. She now supports expanding databases to included arrested criminal suspects.

"My daughter gave up her most basic constitutional right -- the right to live," she told CNN. "They are so many heinous criminals that are being arrested, and not being identified as having committed these [other] crimes. They are being released and they reoffend. ... And we need to stop them earlier because they reoffend and they kill and they rape."

Fourth Amendment test

But privacy advocates warn a final ruling in the state's favor could open the gates to greater government use of one's biological makeup, for a variety of non-criminal purposes.

"The Constitution says police must have some level of suspicion and we know that intuitively," said Erin Murphy, a New York University law professor and national expert on forensics evidence. "If someone is arrested for drug possession, driving under the influence, writing a bad check, for jaywalking-- they don't have all their private information exposed to the police. The police have to have suspicion if they then want to then go search the individual" by taking the DNA sample.

The current case involves a Maryland man convicted of a 2003 rape in Wicomico County in the state's Eastern Shore region. Alonzo King Jr. had been arrested four years ago on an unrelated assault charge, and a biological sample was automatically obtained at that time. That sample was linked to an earlier sexual assault.

King moved to suppress that evidence on Fourth Amendment grounds, but was ultimately convicted of the first-degree rape offense.

Both King and his legal team turned down CNN's request for an interview.

A divided Maryland Court of Appeals later agreed with King, saying suspects under arrest enjoy a higher level of privacy than a convicted felon, outweighing the state's law enforcement interests. That court also said obtaining King's DNA immediately after arrest was not necessary in identifying him, and that the process was more personally invasive than standard fingerprinting.

State officials then asked the justices to intervene, saying the state court ruling "has resulted in the loss of a valuable crime-fighting tool relied upon by Maryland." They said that from a law enforcement and forensic perspective, there is no difference between fingerprinting and collecting "biometric information."

Chief Justice John Roberts last July allowed the Maryland law to stay in effect until a full appeal could be filed. The high court then agreed to decide the constitutional issues. Roberts at the time hinted his tentative support.

Oral arguments on Tuesday

"Collecting DNA from individuals arrested for violent felonies provides a valuable tool for investigating unsolved crimes and thereby helping to remove violent offenders from the general population," Roberts wrote. "Crimes for which DNA evidence is implicated tend to be serious, and serious crimes cause serious injuries. That Maryland may not employ a duly enacted statute to help prevent these injuries constitutes irreparable harm."

The chief justice said last summer there was a "fair prospect" the Supreme Court would ultimately find in favor of the state on the search and seizure questions. Oral arguments will now be held Tuesday, with a ruling expected by June.

A 1994 federal law created a national database in which local, state, and federal law enforcement agencies can compare and share information on DNA matches from convicted felons, but courts have been at odds on just when such samples can be collected and the information distributed.

"The (state court) decision below has direct effects beyond Maryland: Because the DNA samples Maryland collects may otherwise be eligible for the FBI's national DNA database, the decision renders the database less effective for other states and the federal government," Roberts wrote.

The state DNA collection law in Maryland is set to expire at the end of the year, but the justices are likely to decide its constitutionality before then.

Sepich recalls the day a decade ago when she learned her daughter had not returned from a party the night before.

Katie's body was found later that day in a Las Cruces city dump. She had been raped, strangled to death, and her body set afire. One of the graduate student's last acts was to preserve her killer's identity. Blood and skin of the killer was under her fingernails, as she scratched the man while fighting back from the attack.

That genetic profile was placed in a nationwide database known as CODIS. Three months after the murder, Gabriel Avila was arrested for a home break-in, but no DNA was taken. The Mexican national made bail and fled. Sepich says he was allowed to roam the streets for three years before his recapture and 2006 conviction prompted an automatic DNA swab.

Sepich and her family meantime tried to make sense of the murder and turn it into something positive, in Katie's memory.

"It was at that time I learned that DNA was not used like fingerprints. It wasn't taken upon felony arrest," said Sepich. "And I was so convinced of its effectiveness. That's when our family started our quest to see DNA taken upon arrest in all 50 states. Our home state of New Mexico did that in 2006 and we've just continued to work to see other states passed."

Just 11 months after Katie's Law was signed in New Mexico, Avila's genetic markers were linked to Katie's murder. He then pleaded guilty and was given 69 years behind bars. The prosecutor in that case is now New Mexico Gov. Susana Martinez, a Republican.