James McLynas was driving his Ford Explorer across the Howard Frankland Bridge on Oct. 30, 2013, when he noticed a pickup truck behind him. As he pulled into a transmission shop in St. Petersburg, several other cars swarmed the parking lot. Plainclothes Pinellas sheriff's deputies approached him.

"I hadn't even gotten my car fully stopped when I was surrounded," he said.

McLynas, 57, was arrested on several felony charges, including battery, title fraud and grand theft motor vehicle. Months later, records filed in his case didn't explain how deputies found him.

But this year during a deposition, a Pinellas sheriff's deputy testified that the agency used a highly sophisticated cellphone tracking device, called a Stingray, to find McLynas.

It is the first time that public records confirm that the Sheriff's Office uses this technology. Courts across the country, as well as the American Civil Liberties Union, have raised concerns about the Stingray device, also known as a cell site simulator. It can collect data from bystanders' phones, and some law enforcement agencies have used it without a warrant, leaving lawyers and judges in the dark about its capabilities.

"That's a very troubling practice. It's essentially a fraud in the courts," said ACLU staff attorney Nathan Freed Wessler. "If defense attorneys, the courts and the Legislature are none the wiser because it means nobody can bring a court challenge, nobody can try to impose legislative regulation and police are going their merry way, unfortunately, outside the bounds of the Constitution."

Pinellas Sheriff Bob Gualtieri acknowledged his agency owns one simulator but said department policy requires that deputies seek a court order to use it.

Some lawyers question whether that is enough.

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A Stingray is about the size of a stereo, can cost about $200,000 and is manufactured by Harris Corp., a communications technology company headquartered in Melbourne. A spokesman declined comment.

In his March 8 deposition, Pinellas sheriff's Sgt. Matthew Wroe explained how the equipment works. First, deputies request a court order to obtain incoming and outgoing data and cell tower locations of the phone. If a judge grants it, the order is sent to the suspect's cellphone provider.

Once deputies know what cell towers the phone has connected to in the past, they visit that area and turn on the simulator, which acts as a fake cell tower. Nearby phones connect to the device, draining their batteries and disrupting service. Unlike a cell tower, which provides a general location of a phone, the Stingray gives a precise location.

On the day deputies tracked McLynas, court records show, T-Mobile alerted investigators that he was near a cell tower in Hillsborough County. They deployed the Stingray, which gave them an exact location, and followed McLynas to Pinellas.

The Sheriff's Office bought its Stingray about five years ago, Gualtieri said. Although there is no internal policy regulating its use, the device is usually deployed only in felony cases, including some homicides, he said.

"It's extremely worthwhile, and it's been extremely productive for us," he said. "There are a number of times that we've been able to use it and take people into custody for some very serious crimes."

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Cell site simulators are veiled in secrecy.

In 2014, the ACLU sent requests for records related to Stingray use to several Florida police agencies and learned that the Florida Department of Law Enforcement had used the technology more than 1,800 times. In Tallahassee, police deployed it more than 250 times. Miami-Dade police used it 59 times in closed criminal cases in one year.

But many agencies refused to disclose documents. Before departments can buy the equipment from Harris Corp., they must sign nondisclosure agreements with the FBI. The Pinellas Sheriff's Office entered into the same agreement, Gualtieri said.

The Sheriff's Office denied the ACLU's request, saying the documents described active criminal intelligence information and surveillance techniques that are exempt from Florida public records law.

When attorneys start asking questions about how their clients were located, many criminal cases are dropped, Wessler said.

"They don't want the bad guy to hear about what they're doing, which there may be a little legitimacy to that," said John Sawicki, a Tallahassee-based computer forensics analyst who studies Stingray cases. But there's also the lack of oversight, he said. "How do you challenge the search that you never learned occurred?"

With more records surfacing in recent years, regulation of the technology is emerging.

Last September, the Department of Justice started requiring that its investigators get warrants. The Maryland Court of Special Appeals made a similar ruling last month.

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Months after his arrest, McLynas of Indian Shores read articles about cell site simulators and told his attorney, Jerry Theophilopoulos, he suspected this is how deputies found him.

The charges against McLynas are not particularly violent crimes. His charges of grand theft auto and title fraud stem from accusations that he called a wrecker to tow a 1995 Mitsubishi that had been sitting near his home, police reports state. Deputies said McLynas identified himself as the owner, but Theophilopoulos disputes that allegation.

He was also arrested on a battery charge, accused of spraying a Realtor's feet with a garden hose after she entered the property McLynas was living in believing that it was empty, court records state.

"This is not something that you're supposed to use on an average citizen," McLynas said of deputies' use of the Stingray. "I was accused of maliciously misting somebody with a garden hose."

In the battery case, Theophilopoulos filed a motion last year to compel any evidence related to Stingray use. The judge granted it, but prosecutors dropped the charge, records show.

Charges of title fraud and grand theft auto remain against McLynas. Theophilopoulos filed another Stingray motion. The same judge granted it again. He received a copy of the court order granting the Sheriff's Office permission to track McLynas.

Gualtieri, a lawyer, said the order shows the probable cause of the case and the 13-page application outlines the charges against McLynas.

But Sawicki, who is also a lawyer, said the order doesn't request permission to use a Stingray.

"They're not asking to do anything even closely related to a Stingray," he said after reading the order. "They appear to be misleading the court. There isn't anything in here that identifies the methods that they're going to go about doing this."

When asked why the order doesn't mention the Stingray, the sheriff said his agency doesn't have to specify its methodology.

"Once the order is issued telling you you can do it, how you do it is left to law enforcement," Gualtieri said.

Theophilopoulos also raised concerns that the Stingray records weren't submitted in court in the first place, pointing to Florida's rules of criminal procedure, which state that prosecutors have to disclose "electronic surveillance."

"That should have been turned over immediately," he said. "The sheriff is hiding the ball, and it's scary to think of how many citizens have been affected by this technology and they'll never know."

Gualtieri said those records are not part of the case because they're not relevant to the charges. Pinellas-Pasco State Attorney Bernie McCabe agreed.

"We know they got a defendant arrested. Really, I don't know that I'm terribly concerned how they found (the suspect)," McCabe said. "That's not of evidentiary value. They committed whatever they're charged with committing before that."

Contact Laura C. Morel at lmorel@tampabay.com. Follow @lauracmorel.