The Bensalem Police Department, Bucks County's largest, has been collecting DNA from suspects who voluntarily provide it since 2010. The department has amassed some 3,000 individual profiles, Public Safety Director Fred Harran said. So far, it has led to the arrests of more than 100 people, many for lower-level crimes such as burglary.
The database and others like it across the country are designed to catch criminals who often fly under the radar of national and state DNA collections, which contain the genetic material of more hardened felons and sex offenders.
"This is another tool in the arsenal to fight crime," Harran said. "Our program is a voluntary program. And people give up their DNA."
The department is one of at least nine local law enforcement agencies in the United States with such a database. That number is expected to grow, given the Supreme Court's ruling this month that police can collect DNA from people arrested for serious crimes.
The court decision does not explicitly address databases composed of voluntary DNA samples, such as the one in Bensalem. But legal experts believe the ruling approves the use of DNA by police to identify suspects and others in the same way fingerprints have been used for decades.
"By adopting that rationale, it's only going to encourage local police departments to continue to be aggressive with their local databanks," said Stephen Mercer, chief attorney in the forensics division of the Maryland Public Defender's Office, which was involved in the Supreme Court case.
These databases, unlike those on the state and national level, are unregulated, raising concerns about how local departments collect and use DNA.
Mercer said police often ask suspects for a swab without explaining that it will be stored in a database indefinitely or that they have the right to have the material destroyed later because it was given voluntarily.
"How's someone going to ask to have it removed if they don't know it's there to begin with?" Mercer said. "And that's what we're finding with these local databases."
Harran, Bensalem's public safety director, said about 90 percent of people asked have consented to a swab. Each person signs a form that explicitly states the DNA will be used for criminal investigations, he said.
The form does not say the DNA will remain in a police database. And police do not tell suspects they can have their DNA removed from the database, although the department has complied with the small number of people who have made that request, Harran said.
"We're not tricking anybody," he said. "They sign it. They know we're taking it. Do they think we're taking their DNA to send them a Christmas card? We've got to get one up on the bad guy. And right now, we have a great tool with DNA."
He added: "We don't arrest innocent people."
Bucks County Assistant District Attorney Matt Weintraub said that, following national and state database procedures, Bensalem police double-check by taking a fresh swab from anyone whose DNA in the database matches evidence found at crime scenes.
Harran declined to provide the names of people arrested in the township through the department's DNA database.
He said some suspects consent to a DNA swab because they think they won't get caught. They believe police test only blood and other fluids at crime scenes, but officers also collect genetic material left behind by touch.
Harran couldn't explain why others say yes.
"Why would someone with a kilo of cocaine in their trunk give a police officer permission to search their car?" Harran asked, referring to a previous case. "I have no idea. But they do."
Unlike Bensalem's DNA collection, national and state databases are limited by legislation regarding whose DNA is collected.
All states require convicted felons to submit their DNA, according to a Congressional Research Service report. And most states, including Pennsylvania and New Jersey, require misdemeanor sex offenders to provide swabs, as well.
Pennsylvania law does not force people who are arrested to give up their DNA, although a bill pending in Harrisburg would. New Jersey requires DNA collection from those arrested in serious crimes, such as murder, rape, and kidnapping. Those who are exonerated or found not guilty can have their DNA removed from the database.
Bensalem established its collection through LODIS, a lab in Burlington, N.C., that has contracted with eight other departments, though none are in the Philadelphia area, the company said. Harran said having the database costs about $200,000 a year, covered by federal drug-forfeiture money the department receives for being part of a regional task force.
Jay Whitt, LODIS director of law enforcement services, said the lab allows police to catch lower-level criminals.
"Violent offenders are in jail, not out breaking windows," Whitt said. "You're not dealing with Ted Bundys every day. We're dealing with the little rat bastards every day."
Lawrence Kobilinsky, chair of the science department at the John Jay College of Criminal Justice, said more police departments were filling their databases with the DNA of lower-level criminals. The collections will only become larger and more effective, he said.
"They're going to proliferate, there's no doubt about it," Kobilinsky said. "And public beware."
Contact Ben Finley at 610-313-8118, firstname.lastname@example.org, or follow on Twitter @Ben_Finley.