A woman accused of killing her husband is convicted after New Jersey prosecutors reconstruct her movements. Investigators pieced together the driving route of a missing Baltimore federal prosecutor who later turned up dead. Prosecutors in a New York City murder trial discredited a suspect's alibi.
A key factor in these and other cases: E-ZPass, the electronic toll payment system that records when and where the vehicles in question traveled.
As hundreds of thousands of Marylanders hit the road this Labor Day weekend, a growing number will be relying on their E-ZPass devices to speed their way through tollbooths. And as the popularity of the windshield-mounted devices has grown among motorists, so has their usefulness to investigators.
Records of electronic toll payments are popping up in courtrooms as evidence in criminal and civil cases. Like data from ATM transactions and cell phone usage, the toll records can be used as an investigation tool, showing where someone -- or at least someone's car -- was or wasn't at a precise time.
Eugene O'Donnell, a lecturer at John Jay College of Criminal Justice in New York cited a New York Police Department probe that relied on E-ZPass records of employees to reveal that several officers who had put in for overtime had gone home instead.
"If a guy tells you a story that's not true, you can deconstruct a story by the records," O'Donnell said. "It's sort of the opposite of a building block."
O'Donnell warns that the E-ZPass record is no "smoking gun."
"Some people think it's an 'aha' mechanism that makes a case sink or swim," he said. "It could be useful in a roundabout circumstance. It can help to accredit or discredit."
Nowadays, it's easier to track down where people have been, from using credit card transactions, footage from surveillance cameras and E-ZPass records, O'Donnell said.
Maryland, where drivers ring up about 56 million E-ZPass transactions a year, is one of seven states in which toll records can be subpoenaed in criminal and civil cases.
"It's not something we discount. We use the E-ZPass to help with investigations to find out where a person has been," said Cpl. Michael Hill, spokesman for the Baltimore County Police Department. "The only thing that E-ZPass tracks is the vehicle, not the person."
Sgt. Christina Presberry, Harford County sheriff's spokeswoman, said E-ZPass data are "an investigative tool that we do use, probably not often." She wouldn't comment on the frequency of use.
Transportation officials release E-ZPass records only when a proper subpoena is presented. At the Maryland Transportation Authority, subpoenas are reviewed on a case-by-case basis by operations staff and legal counsel, said Kelly Melhem, the spokeswoman for MdTA. Although the authority does not keep track of how many subpoenas have been received, most of them are for criminal investigations, Melhem said.
The electronic records of the transaction are kept for 18 months if the user has no violations.
E-ZPass became a tantalizing clue for investigators in the still-unsolved death of federal prosecutor Jonathan P. Luna. Authorities recovered a Pennsylvania Turnpike toll ticket that was turned in at rural Ephrata, Pa., and they believe was used by whoever was driving his car on the night in 2004 he drowned in a stream.
Luna, an assistant U.S. attorney based in Baltimore, had an E-ZPass tag, which meant the car could have entered the highway without stopping to take a toll ticket, something that a driver unfamiliar with the vehicle might not have known.
Investigators established a timeline of Luna's activities the night he died using records from credit cards, an ATM and the time he passed through tolls. Michelle Crnkovich, FBI spokeswoman for the Baltimore office, said the E-ZPass data were a "resource."
E-Z Pass was first used in New York in 1993, and today there are 9 million users who rang up more than 2 billion transactions in 2006, according to the E-ZPass Interagency Group, an Atlantic City, N.J., organization comprising 23 agencies in the 12 states where the system is in use.
The 16 million devices in use are radio-frequency identification transponders that communicate with reader equipment installed in toll collection sites.
Despite the volume of transactions, the organization has gotten only a smattering of requests from law enforcement authorities for records, said James Crawford, executive director of the E-ZPass Interagency Group. And while useful, the data can be less revealing than other modern types of technology tracking, like cell phone records.
"The difference is that cell phone records tell you who you actually called," Crawford said. "This tells you that [your transponder] went through certain toll plaza at a certain time."
As the use of electronic tolls spreads, some are sounding warnings on the effect on privacy.
"Our society has to adjust to the fact that law enforcement uses these breakthroughs," said Avi Rubin, a technical director of Information Security Institute at the Johns Hopkins University. "Many conveniences have unfortunate side effects of more risks to privacy."
Aaron Quinn, a spokesman for National Motorist Association, a drivers advocacy group based in Waunakee, Wis., said drivers are "trapped in this surveillance."
"They don't consent to having this used against them," Quinn said.
But the vast scale of the system in this part of the country should temper concerns about privacy, Crawford said.
"Our greatest fear is that people are saying, 'Oh my God, Big Brother is watching us,'" he said. "But there are so many transactions, nobody has time to watch. It would be physically impossible."
For drivers concerned with protecting their privacy, Quinn recommends paying with cash, even if that means waiting in longer lines.
"Lots of times, there are incentives and it is more convenient," he said. "At this point, you can avoid it by doing it manually and staying out of the system."
The flip-side of the use of E-Z Pass data in court cases was illustrated in a Maryland case last year. A pair of New Jersey grandparents suing for visitation rights used their records as evidence of their devotion to their grandchildren.
Sun reporter Josh Dombroskie contributed to this article.
During the Labor Day weekend, 652,000 Marylanders are expected to head out for holiday trips, traveling 50 miles or more from home. Here's how they will travel:
Car, truck or RV: 544,000
Train, bus or other: 30,000
Vacationers hitting the road will find gas prices in Maryland at a five-month low:
Yesterday: $2.66 per gallon (average for self-serve regular)
July 4: $2.94
Memorial Day: $3.13
Last year: $2.87
National average yesterday: $2.77
Highest average U.S. price: Hawaii, $3.24
Lowest: South Carolina: $2.54
Maryland rank: 40th most costly
Source: AAA Mid-Atlantic