By the time the hangman finished him off, Jonathan Wild had few friends. In his own way he had been a public servant—a combination bounty hunter and prosecutor who tracked down thieves and recovered stolen property, a useful figure in 18th-century London, which had no formal police force of its own. Such men were called "thief-takers," and Wild was good at his work. But along the way, he became more problem than solution.

He called himself the "Thief-Taker General of England and Ireland," but he became London's leading crime boss, specializing in robbery and extortion. He frequently encouraged or even set up thefts and burglaries, fenced the booty for a relative pittance, then returned it to its owner for the reward. If his cronies tried to double-cross him, he had them arrested, to be tried and hanged—then collected the bounty. It was said that he inspired the term "double-cross," for the two X's he put in his ledger beside the names of those who cheated him.

Daniel Defoe, a journalist as well as the author of Robinson Crusoe, wrote a quickie biography of Wild a month after he was hanged, in 1725. Henry Fielding, the author of Tom Jones and Joseph Andrews, satirized him in The History of the Life of the Late Mr. Jonathan Wild the Great. John Gay took him as his inspiration for the villainous Peachum in The Beggar's Opera.

But by the time that work had morphed into the Bertolt Brecht-Kurt Weill hit The Threepenny Opera two centuries later, Wild had all but faded from memory. And when Bobby Darin made a hit out of "Mack the Knife" 30 years after the play opened, Wild was largely a forgotten man.

But thanks to a pair of expatriate Americans fascinated by the way England's other half lived during the Age of Enlightenment, anyone with a computer can now resurrect Jonathan Wild and his dark world. The original record of his trial is in the Proceedings of the Old Bailey, the digest that described and often transcribed the more than 100,000 trials that took place in the criminal court of the City of London and the County of Middlesex between 1674 and 1834. Working with grants totaling some $1.26 million, historians Robert Shoemaker of the University of Sheffield and Tim Hitchcock of the University of Hertfordshire have digitized the 52 million words of the Proceedings—and put them in a searchable database for anyone to read on the Internet.

Built in 1539 next to Newgate Prison, the justice hall was nicknamed after its address on Old Bailey Street, where London's "bailey," or wall, once marked the city's Roman boundaries. The court tried felony cases—which included any case that carried the death penalty—and in a city where criminals' biographies and elaborate ballads routinely chronicled the exploits of famous malefactors, the Proceedings were a tabloid-style sensation.

The Proceedings' first issues were thin, cheap and focused on sex and violence, but as time passed, they became more comprehensive and formal, eventually acquiring the stature of an official record; Shoemaker and Hitchcock call them "the largest body of texts dealing with non-elite people ever published." Non-elite indeed! The court records document a tough, teeming London just beginning to flex its muscles as the commercial center of the Western world. The Proceedings made a profit virtually from the first pamphlet issued and thrived for decades afterward. It's easy to see why.

Take the case of 19-year-old Elizabeth Canning, who vanished in 1753, only to stumble home a month later dressed in rags, half-starved and bleeding from the head. She said she'd been robbed and kidnapped by gypsies and held in a hayloft at a rural brothel for 27 days after refusing to become a prostitute. "There was a black pitcher not quite full of water, and about 24 pieces of bread" in the loft, she testified in a case that riveted the public for months. She claimed to have subsisted on these meager rations until she escaped by tugging a plank from a boarded-up window and dropping about ten feet to the ground, cutting her ear in the process.

Mary Squires, the accused ringleader in the crime, maintained that she had never laid eyes on Canning before the trial, but was convicted of robbery—a more serious charge than kidnapping at the time—and sentenced to death anyway.

It then became clear that Canning's story had serious holes. Besides the implausibility of her prolonged survival on so little food, evidence revealed that neither Squires nor her accused accomplices were anywhere near the farmhouse at the time of Canning's purported kidnapping. Investigators visited the loft and said it bore little resemblance to the room Canning had described, and tenants there testified that they had been in residence during the time Canning said she had been locked up. The loft indeed had a small window, but it also had a second, much larger, unboarded one that offered easy access to the yard four—not ten—feet below.

In a second trial, Canning was convicted of perjury and "transported" to the American Colonies. There, she married the great-nephew of a former governor of Connecticut, bore five children and died in 1773, before she turned 40. (No one ever discovered what had really happened to her during her disappearance.) Squires was pardoned and released.

The stories in the Proceedings evoke the mean streets of Moll Flanders, the waterfront of Jim Hawkins, Black Dog and Long John Silver and the dank alleyways where Fagin and the Artful Dodger ran gangs of "blackguard" orphan cutpurses.

In 1741, for example, highwayman John Car was sentenced to death after mugging a man in a park for four shillings and shooting him in the eye. Passersby ran Car down, and when one of his pursuers asked why he had done it, the thief offered an explanation worthy of Dickens: "Money, if you had been here, I would have served you the same."

In 1761, Thomas Daniels was convicted of murder for throwing his naked wife, Sarah, out of a third-story window one August night after returning from a pub. But he won a pardon after documenting his spouse's vicious temper and claiming that, on the night in question, she whacked him over the head with an unidentified object, then ran to the window and "flew out."

The Proceedings have long served as primary source material about daily life in 18th-century London, but their riches were laid bare only to those dogged enough to leaf through hard copies in the bowels of research libraries or, since 1980, to squint for hours at microfilm. "I read them page by page," says University of Toronto emeritus historian John Beattie. He began in the 1980s, researching Crime and the Courts in England 1660-1800, and finished in the '90s, while writing Policing and Punishment in London 1660-1750.

But by transforming the Proceedings into Oldbaileyonline.org, Shoemaker and Hitchcock have brought them to the laptop of Everyman and demonstrated how computer science can make the past come alive.

It is now possible to place software "tags" in large bodies of digitized data, allowing researchers to find something simply by asking the computer to retrieve it. Such high-speed searches have been used not only to sort archives but also to search telephone records, catalog fingerprints or accomplish virtually any other task requiring navigation of immense masses of data. But it wasn't that way when Shoemaker and Hitchcock began their careers in the late 1980s.

"When I interviewed for my first lectureship, they asked me if I could teach 'computing in history,'" says Hitchcock. "I said 'yes' because I wanted the job, even though it wasn't true. On the computers of that time they had developed programs that allowed you to flit from page to page. You could see the potential, but not the mechanism."

Hitchcock, who is from San Francisco, and Shoemaker, who grew up in Oregon, met in 1982 as doctoral candidates in the Greater London Record Office in the basement of County Hall. Both were interested in what Hitchcock calls "history from below"—he was writing a dissertation on English workhouses in the 18th century, and Shoemaker was studying the prosecution of petty crime in the Greater London area during the same period. The two helped edit a book of essays published in 1992, then developed a tutorial on 18th-century English towns on CD-ROM in the mid-1990s. Within a few years, the Internet had provided the "mechanism" Hitchcock needed. "The Old Bailey proceedings seemed a natural," he says.

The pair conceived the idea of digitizing them early in 1999, then spent a year doing background research and writing grant proposals. They got $510,000 from the Arts and Humanities Research Council, the British equivalent of the National Endowment for the Humanities, and $680,000 from the New Opportunities Fund, established for "digitization of learning materials." The universities of Sheffield and Hertfordshire contributed staff, equipment and space.

"It was an enormous amount of money, and we were lucky," Shoemaker says. They enlisted Sheffield's Humanities Research Institute to customize software for searching the Proceedings, but first they needed a digitized copy of the text.

There was no easy way to get one. Technology in 2000 wasn't sufficiently sophisticated to scan words off microfilm; even if it had been, the vagaries of 18th-century printed text, rife with broken fonts and ink "bleed-throughs" from the other side of the page, would have made the technique impossible to use.

So the researchers hired someone to take digital photographs of all 60,000 microfilm pages, then sent the images on CD-ROMs to India. There, in a process known as double re-keying, two teams of typists typed the entire manuscript independently, then fed the copies into a computer that highlighted discrepancies, which had to be corrected manually. That took two years and cost nearly half a million dollars. Then Shoemaker and Hitchcock assembled a team of researchers to embed the entire manuscript with over 80 different computer "tags," permitting searches by such categories as first name, surname, age, occupation, crime, crime location, verdict and punishment.

The Proceedings went on-line in stages between 2003 and 2005. The Sheffield techs refine and update the software continually, recently adding links to maps to help people locate crime scenes more effectively. Their next task is to link stolen objects mentioned in the Proceedings to images of them in the Museum of London.

Meanwhile, the team has obtained enough new grant money to digitize the proceedings of the Old Bailey's successor, the Central Criminal Court, whose 100,000 trial records begin in 1834 and go to 1913. These should come on-line in 2008. The two also plan to digitize an additional 30 million words of 18th-century records—among them, the records of the carpenters' guild, Bridewell Prison and the insane asylum known as Bedlam—to be integrated into the original project. "It will allow us to trace people through the system," says Hitchcock, "to create a kind of collective biography of working people in 18th-century London."

With Oldbaileyonline.org, the haystack now readily surrenders its needles. Genealogists routinely search it to trace family histories. One scholar searched it for information on the court's treatment of "idiots"—people with cognitive disabilities. A few strokes on the keyboard can yield statistics for burglary (4,754 cases in the database), murder (1,573), arson (90), forgery (1,067) and other crimes, or produce a map where crimes were committed. Oxford English Dictionary etymologists found that the expression "No way"—thought to have emanated from the University of South Dakota in the 1960s—seems to have arisen during an Old Bailey rape case in 1787.

Oldbaileyonline.org "broadens the perspective," says the University of Oregon's Randall McGowen, who is writing a history of 18th-century forgery. "You can find out that forgers were overwhelmingly male." (Most were clerks with a weakness for gambling or women and the ability to mimic the boss's handwriting in a "note of hand," the IOU's that the wealthy passed around to obtain funds.)

Traditionalists note that technology of any kind—from microfilm to the Internet—adds "distance" to scholarship, not necessarily a good thing. Though the University of Toronto's Beattie finds the Internet "indispensable" for his current research, he says, "it's a pleasure to pick up a letter actually written by Henry Fielding, and I've taken the string off bundles of documents that still had the 18th-century dirt on them."

The London described by the Proceedings was the hub of a nation that catapulted into the front rank of world powers in the 18th century. The city's population, almost 600,000 in 1700, grew to more than a million by 1800, and the economy exploded.

With no formal police force, Londoners at the dawn of the century had to protect themselves. Neighborhoods appointed householders as "constables" who had the authority to arrest evildoers or summon assistance. Citizens were required by law to heed the "hue and cry" of "Help!" or "Stop, thief!" and run the criminal to ground, as they did in the case of John Car.

With such rudimentary policing, the government focused on deterrence, and under the so-called "Bloody Code," a succession of laws enacted through the mid-18th century, more than 200 offenses carried the death penalty. These included not only violent crimes, but also everything from forgery to shoplifting and pickpocketing.

"Execution was used to scare people by example," Shoemaker says, but since neither the authorities nor the public wanted to hang people for relatively insignificant crimes, only about a third of death sentences were actually carried out during the 18th century, and public enthusiasm for hangings waned as the century progressed.

"Nobody wanted a blood bath," Shoemaker says. Instead, many capital offenders were branded and some were pardoned, while others were "transported" to the North American Colonies, and, later, to Australia. Imprisonment became a more frequent alternative only in the 1770s, when the American Revolution disrupted transportation.

Even with the Bloody Code, there was no formal system of investigation or prosecution, so the government began offering large bounties for conviction of those guilty of serious offenses. London attracted young working people, who were busy in boom times but idle and often dangerous during busts. Wars were fought serially, and each treaty brought a wave of demobilized soldiers whose most marketable talent was skill with weapons.

Crime became more violent, and new methods of law enforcement were needed. One of the innovators was Henry Fielding, who, with his half-brother John, served as a mid-century magistrate at Bow Street, near Covent Garden. The Fieldings induced the government in 1753 to fund the Bow Street Runners, a corps of ex-constables, to track down miscreants and bring them to justice. "They were real detectives going after criminal gangs," says Beattie, who is writing a history of the runners.

And they supplanted the thief-takers, who, thanks to Jonathan Wild and others, had become hopelessly corrupt holdovers from simpler times.

The crime that undid Wild, which began January 22, 1725, was modest enough. Irish immigrant Henry Kelly testified that he and his friend Margaret Murphy had been drinking gin at Wild's house when Wild suggested the two rob a shop run by a blind lacemaker. "I'll go along with ye, and shew ye the door," he told them.

Wild waited outside while Kelly and Murphy went in. Shopkeeper Katharine Stetham later testified that the pair were "so very difficult" that none of her samples "would please them." She went upstairs and found others more to their liking. But "we could not agree about the price," Stetham testified, so Kelly and Murphy left. A half-hour later, Stetham "miss'd a tin box of lace."

After leaving the shop, Kelly and Murphy met back up with Wild. Kelly later testified that Wild offered to pay them on the spot "three guineas and four broad pieces" (a bit over seven pounds—a year's wages for a housemaid) for the box of lace, or they could hold out for the possibility of getting more if Stetham offered a reward. Kelly said they took the cash.

Stetham, not surprisingly, turned to Wild for help. She advertised a reward of 15 guineas and, according to her testimony, told Wild privately that she would give 20 or 25.

Wild, presenting himself as an honest officer of the law, accepted only ten guineas from Stetham—ostensibly to pay off an intermediary—and, in due course, produced the missing lace. "Not a farthing for me," he told her, according to her testimony. "I don't do these things for worldly interest, but only for the good of poor people."

But Kelly and Murphy told a different story, one the jurors found persuasive, at least in part. They acquitted Wild of theft, but convicted him of an offense that would come to be known as "Jonathan Wild's Act"—perverting justice by accepting a reward without attempting to prosecute the thief.

Wild was hanged at Tyburn on May 24, 1725. The route from Newgate to the gallows was lined with cheering crowds "who called furiously upon the hangman to dispatch him," Daniel Defoe wrote. The Proceedings summed up the case with typical economy: "The jury acquitted the prisoner of the first indictment [theft] and found him guilty of the other. Death."

Guy Gugliotta, a former reporter for The Washington Post, makes his Smithsonian debut with this article.