By that time, the victim had long thought she had heard the last from police.

"I will never forget, but I tried to move on with my life," she said recently. "It all came back up when the detectives came and knocked on my door."

Maryland's new DNA sampling law had been in effect less than two months when Brown was arrested on six charges related to his alleged sexual abuse of 7- and 8-year-old relatives in his Lansdowne apartment, according to court records.

On Feb. 25, 2009, an officer in Baltimore County swiped a cotton swab on the inside of Brown's cheek. That sample was sent to a lab to be tested and the results were entered into a statewide cold case database.

The sample matched two unsolved cases: the 2004 rape in Cherry Hill and a similar case involving a 14-year-old girl on Aug. 11, 2000, near Lake Montebello in Baltimore. The teen was attacked after she accepted a ride in a station wagon while waiting for a bus at 33rd Street and The Alameda, according to police records.

Brown has steadfastly maintained his innocence in each of the cases.

Detective Smith, then a 15-year veteran of the Baltimore Police Department, had been assigned to the 2004 case. She drove to the victim's house, slipped her business card in the victim's front door and waited for a call.

On June 9, 2009, Detective Smith and her partner arrived at the young woman's house with a printout of six photos, one of which pictured Brown. Smith had used a computer program to create the photo lineup, selecting photos of Brown and five other men with complexions, features and hairstyles similar to his.

The victim slid into the back seat of the police cruiser and Smith handed her the printout, face down.

"She flipped it over and she became visibly upset," Smith said at Brown's trial. "She cried and she identified Mr. Brown as the person who assaulted her."

The victim circled the photo of Brown, signed her name next to it and on the back she wrote, "He is the guy who raped me."

Legal implications

Brown was already serving a year in prison on a fourth-degree sex offense — for the incidents involving his young relatives — when he was found guilty in October 2010 of first-degree rape in the Cherry Hill case. He was sentenced to 60 years in prison for that rape, and later agreed to serve 20 years, concurrently, in the 2000 rape.

But his fate may rest on a challenge to Maryland's DNA sampling law in a similar case

In that case, Alonzo Jay King Jr. was arrested in 2009 on assault charges, and police collected a DNA sample from him. It linked him to the 2003 rape of a 53-year-old woman in her Salisbury home. The Court of Appeals ruling reversed King's rape conviction and sent the case back to the lower court for retrial.

After that ruling, Maryland authorities stopped collecting post-arrest DNA samples, pending the outcome of the state's expected appeal to the Supreme Court.

About half of the states and the federal government allow police to take DNA samples when a suspect is arrested. But when those laws have been subject to legal challenges, federal appeals courts, and lower courts across the country have ruled both for and against the practice.

If the Supreme Court tackles the issue — by no means a certainty — its decision will affect the role genetic technology can play in solving crimes.

Catching a criminal does not give police the right to violate constitutional freedoms, contend the law's opponents, including Stephen B. Mercer, chief attorney for the forensics division in the Maryland Office of the Public Defender. A person's DNA contains information not available in a fingerprint, including determining one's relatives, race and future health problems, he said.

"If catching criminals is all that this debate is about then warrantless entries into homes should be OK, redlining neighborhoods and warrantless pat-downs of people is OK," Mercer said. "Listening in on phone calls, reading mail, searching through financial records and scrutinizing medical records, all of that should be OK.