Suspected dog fighter Leroy Longs Jr. allegedly made 259 trips between July and mid-November to five addresses in Minneapolis where he kept pit bulls, each animal padlocked to a chain embedded in concrete or attached to a tire iron.

Minneapolis police covertly followed Longs’ movements using a GPS tracker placed on his car without his knowledge, evidence that was key to rescuing 13 adult dogs and five puppies and arresting and charging Longs for animal fighting. It’s the same tool that was used to track a suspected heroin trafficker between St. Paul and Chicago twice in October, and one the Ramsey County Sheriff’s Office employs about once a month in “bait cars.”

The technology has been used for about a decade by agencies ranging from the FBI to local police, and it will continue to grow in use, some authorities said. Police say that GPS tracking allows them to conduct the type of surveillance that would require multiple officers and hours of labor, which can be difficult to staff and fund as budgets shrink, and that public privacy is protected by a number of measures.

“Ten years ago, [GPS tracking] was unheard of,” said Minneapolis police Lt. Mike Fossum, commander of the department’s weapons unit. “It’s almost worth its weight in gold. There’s a legitimate law enforcement purpose for it, and it’s serious crimes.”

However, critics worry that it’s becoming part of America’s surveillance culture.

Chuck Samuelson, executive director of the American Civil Liberties Union of Minnesota, said authorities need to be mindful about data collection.

“My problem is, once again, it’s another case of technology driving policy,” Samuelson said. “They’re not doing things to save money, they’re doing it because they can.”

Law enforcement authorities interviewed for this story declined to say how many trackers their departments own, citing concerns about revealing too much information about their capabilities to criminals. The Hennepin County Sheriff’s Office, which polices Minnesota’s most populous county, issued a two-sentence e-mail statement and declined to be interviewed.

“It is a sensitive subject,” said FBI spokesman Kyle Loven. “There are certain specific aspects of it that we like to keep in-house.”

The tracking devices vary in size from larger units that are wired into a vehicle’s engine compartment to smaller ones that adhere to a vehicle’s metal undercarriage. They are installed without the suspect’s knowledge while the vehicle is parked in a public location. The process can take just seconds, Fossum said.

Agencies own or share the devices and pay for satellite tracking time. GPS coordinates can be tracked in real time or in increments. Officers can also collect and review the data at a later date.

When the Ramsey County Sheriff’s Office sets up “bait cars” with GPS tracking to catch car thieves, a deputy in an office tracks the movement on a computer or a deputy tracks it from the field, said sheriff’s spokesman Randy Gustafson.

“We’re not tracking honest, regular citizens,” Gustafson said. “Hopefully, technology makes you work more efficiently and more effectively.”

Authorities say that checks and balances are in place to protect against abusing the technology and that human surveillance is still required to connect a suspect with a vehicle and throughout an investigation.

In the Longs case, Minneapolis police and animal control officers visited the homes and spoke to informants and witnesses.

Minnesota statutes and a key 2012 U.S. Supreme Court decision require a state or federal judge to approve the use of trackers. Police must present a judge with evidence of probable cause to obtain a warrant or court order to use one.

Those measures do provide constitutional protection, Samuelson said.

“From an ACLU point of view, clearly warrants are a minimum thing and one hopes and one assumes that judges are careful about granting one and are not just reflexively granting them,” Samuelson said.

Used ‘when a case dictates’

It’s difficult to tally exactly how often such warrants and orders are granted in Minnesota because they aren’t labeled in a way that allows them to be easily pulled from other documents. According to the State Court Administrator’s Office, at least 12 were issued by state judges in 2012 and 18 so far this year. That doesn’t show the full picture.

Fossum and Gustafson estimate that their departments each use the technology about a dozen times a year.

“We’re not going to put a number on it,” St. Paul police Sgt. Paul Paulos said of his department’s use of GPS tracking. “This is all done when a case dictates when it needs to be used.”

Details about GPS tracking in Longs’ case were revealed in related warrants filed to search the homes and premises where Longs allegedly kept dogs.

Authorities say GPS won’t replace traditional surveillance and investigatory techniques, but Mankato defense attorney Christopher Rosengren said GPS has limitations and moves cases into new territory.

Rosengren is representing Jeffrey E. Matthews of New Ulm, Minn., who is charged in Watonwan County based partly on GPS evidence.

“The reality is corners are cut, and because of the lack of case law out there [on GPS tracking], judges don’t know how to handle it,” Rosengren said of how long, how often and under what circumstances the technology should be used. “There needs to be a sort of balance with the Fourth Amendment.”

GPS was used to track Matthews, 54, a county welfare fraud investigator, from July 18 through Aug. 12 this year because of suspicions he wasn’t working. Watonwan County Sheriff Gary Menssen followed him for five days before a GPS tracker was installed on Matthews’ Buick at 11:56 p.m. on July 18, court documents show.

Tracking led to charges

GPS traced Matthews’ car moving between several locations, including his home, his office in St. James, Minn., a New Ulm cemetery where he allegedly slept or read during the workday, and a park in Sleepy Eye, Minn. He allegedly went home early on several days. He was charged with theft by swindle and misconduct of a public officer or employee.

Rosengren filed a motion to dismiss the charges, arguing that GPS coordinates don’t prove that Matthews wasn’t working. (Investigators also followed Matthews a few times after the GPS tracker was installed.) Matthews travels regularly for his job, Rosengren said. The motion was denied.

“We’re getting into territory that, due to technology, we never had before,” Rosengren said. “[GPS] doesn’t necessarily prove that you were doing anything. It doesn’t monitor your voice. It has limitations, and it does raise privacy concerns, and I think, proof concerns.”