The immediate causes of the civil unrest in Cincinnati this past spring are clear enough: White cops had been abusing and killing black civilians. But why such police racism; was it too few officers of color, a weak civilian review process, racist media?

Or was it genetic? Is racist terror embedded in the political DNA of American policing? After all, the basic patterns of harassment that triggered the mayhem in Cincinnati are some of the oldest and most consistent in US history. Typically the story of policing starts with the village-watch systems of the colonial Northeast, then moves to the formation of the first municipal constabularies in New York, Boston and Philadelphia.

But the real origins of today's "Five-O," "Rollers" or "Po-Po" lie with the slave patrols of the Old South. By the time of the Civil War, every county of the South deployed patrollers–or "pattie rollers" as African-Americans sometimes called them. These protocops, ubiquitous posses of armed white men, were the frontline defense against slave rebellions. They worked only at night, riding from plantation to plantation, stopping black people, searching their homes for contraband and whipping any slave caught traveling without a written pass.

As the immediate agents of a white supremacist state, slave patrols imbricated violence and racism into everyday life. They were crucial to the reproduction of slave society and slave labor power, and served as ideological invigilators in the construction of a paranoid and hate-fueled caste system that persists to this day. The patrols were central to southern society, but only now do we get the first book-length examination of this antebellum gendarmerie. Prior to Sally Hadden's Slave Patrols: Law and Violence in Virginia and the Carolinas there were only a few short monographs from the turn of the century (which Hadden addresses) and a few chapters in a lost and barely read book, Police and the Black Community, by Robert Wintersmith (which, surprisingly, Hadden does not address).

Along with the obviously racist dynamics of modern policing, patrollers left us some specific concepts, like the police "beat." Pattie rollers had "beats"–defined areas of operation–and worked in small mounted groups called "beat companies." While the patrollers' main task was controlling African-Americans, this also required the control of whites. In many Southern counties all white men were forced to serve in the patrols, and in some counties all white men were required by law to stop and check the passes of any black people they met on the road at any time. This was nothing short of state enforced racism.

A fairly straightforward history, Slave Patrols begins with a look at the policing of slaves on Barbados, where the very first patrols were established in response to an aborted slave revolt in 1649. After that many Caribbean planters decamped to the Carolinas, bringing with them slaves and the political technology of slavery: curfews, passes, patrols and militias. Fundamentally, the patrols were a premodern system of surveillance and policing designed to restrict slave mobility–a crucial source of African-American social power.

Along with maintaining familial and romantic ties, black mobility produced a vast network of interpersonal connections–the circuitry of resistance–through which flowed news, plans, supplies, weapons and people. Mobility was also crucial to the sub rosa economy, of nighttime reexpropriations from the master's stores, fencing pilfered goods, trading produce for liquor with poor whites and practicing traditional medicine. And restricting mobility limited slave contact with Native Americans and the fugitive slaves who (at least in the colonial era) lived as social bandits on the edge of the plantation world. Containing and limiting this informal resistance and its enabling underground milieu helped prevent formal organized resistance like escapes and armed rebellion.

By 1680 Virginia had also instituted patrols and required both slaves and white indentured servants to carry passes when traveling, and over the next century the whole South became increasingly militarized. Hadden's account of this buildup shows a cyclical escalation in which slave revolts or plots led to white panic, ramped-up vigilance and a reinvigoration of patrols. Heightened security was usually followed by increased calm, declining vigilance and then more resistance.

The trend toward ever more organized control in the South accelerated after the Revolutionary War (during which more than 3,000 escaped slaves fought for the loyalist Lord Dunmore, who offered freedom in exchange for armed service). In 1777 Vermont had abolished slavery; Pennsylvania followed three years later. From then on the "peculiar institution" came under increased attack, as European powers outlawed the slave trade and more "free soil" and abolitionism emerged in the North. By the early antebellum period, the patrol system had fully evolved throughout Dixie.

A typical night on patrol involved three to six armed white men on horseback riding the country roads in search of black people, stopping at farms and plantations where they were authorized, regardless of the property holder's wishes, to search slave quarters for visitors, escapees or contraband like weapons, liquor, books and excessive provisions that might indicate plans to flee. Violation of local regulations led to on-the- spot whippings.

In some jurisdictions patrollers were paid from local taxes; in others they were paid with bounties for catching "truant" or runaway bondspeople. More often, the patrols were a form of corv?e labor, forced upon the whole white male population by the society's more affluent members.

Before Hadden's book, numerous histories of slavery and black resistance made passing mention of patrols, usually casting them as gangs of poor whites, motivated as much by their own pathology as by legal structures. This fits comfortably with America's official mock-up of the proverbial racist: a blinkered, lowbrow hick. But Hadden takes that myth apart. For example, in Norfolk County, Virginia, where in 1750 half the white population owned no slaves, the bulk of patrollers were men of the solid middle. Plantation plutocrats with twenty or more slaves frequently bought their way out of service while poor whites tended to do as little patrolling as possible. So, the bulk of patrollers were small-town burghers like doctors, lawyers, printers and merchants, or they were prosperous working farmers owning between one and five slaves. It is no coincidence that this same class later formed the base of the Ku Klux Klan during its first incarnation just after the Civil War, and even more so during its infamous second rise just after World War I and into the 1920s.

Hadden's history is very well researched and her writing is smooth, but the book's most interesting political ideas remain only half-exhumed. One wants more discussion of the patrols' cultural impact: They policed "blackness" and the color line, but they helped construct the meaning of "whiteness" as violently anti-black. In fact, some patrols were instructed to attack whites who strayed across the color line: One North Carolina law instructed patrollers to whip any "loose, disorderly or suspected person" found in the company of slaves regardless of the person's color. Unfortunately, Hadden does not thoroughly explore this nexus of violence, the law, race and identity. What the book does offer is a very detailed accounting of who patrolled, how, when, where and under what sort of legal guidance. Embedded within Slave Patrols is the theme of surveillance. The patrols were technologies of observation and intimidation, while the attendant system of slave passes and wanted posters were embryonic forms of identification.

Picking up this history of surveillance and social control, from a different angle, is Simon Cole's Suspect Identities: A History of Fingerprinting and Criminal Identification. Cole's book is a microlevel history of what Foucault called "capillary" forms of power. In particular, Cole focuses on the state's evolving methods of identifying deviants. He begins with the history of criminal identification and judiciary record keeping in the Napoleonic courts and jails around 1808, where convicts were simply listed alphabetically, a system that provided no means to combat false identities. The 1839 invention of photography began to change all that. Starting in the mid-1850s, once daguerreotypes were widely available, police in Europe and America began creating "rogues' galleries" and photo albums featuring known "criminals" and "degenerates." The NYPD, ever innovative, led the way. By 1858 they had 450 "Ambrotype" photos on file. Meanwhile, fingerprint identification was just beginning as an administrative tool in colonial India.

William Herschel, chief administrator of the Hooghly district of Bengal, first started experimenting with handprints on documents to verify the identity of contractors and pensioners (he probably gleaned this technique from similar ancient Hindu practices). His desire for greater control over the local population was fueled in part by the massive Sepoy Rebellion of 1857-8 and the resistance, chaos and widespread fraud that followed in its wake. Herschel's prints helped create "real" identities and thus shored up the power of colonial ledgers and files. As in Hadden's story, we see the double helix of resistance and repression developing together.

Along with Herschel, several other gentlemen were also "discovering" fingerprints: Francis Galton, the father of eugenics and a cousin of Darwin's, started studying fingerprints as part of his work on heredity and race (he never did link print patterns to either), while Henry Faulds, a physician working in Japan, first suggested using fingerprints to identify criminals in an 1880 letter to the journal Nature. Eventually, experts were able to divide all prints according to "loops," "whorls" and "arches." This allowed for simple storage and retrieval. But "dactyloscopy"–as print reading was known–wouldn't become a standard law enforcement tool for almost a generation more.

The height of criminological sciences in the late nineteenth century was "Bertillonage," a complicated, and in retrospect rather silly, system of body measurements developed in France by Alphonse Bertillon, son of one of anthropology's founders. By the 1880s Bertillonage had proliferated throughout the industrialized world, though the system's extremely precise procedures and set of eleven bodily measurements were frequently modified (or mangled) by local police departments and thus rendered useless when exchanged between agencies. To simplify things, fingerprints–infinitely unique and unalterable–got folded into the Bertillon system as a convenience.

Police in India were the first to start fingerprinting, in 1897. By 1901 Scotland Yard had incorporated a form of fingerprinting into its Bertillon system, and in 1906 the New York Police Department did the same. From there, the technique soon eclipsed Bertillonage. By the early 1920s photos and prints made up the fundamentals of criminal identification, and Bertillon had been almost completely discarded. Much of Cole's book concerns itself with the ensuing techno-bureaucratic intrigues and battles among a myriad of different print classification systems and their proponents. These dry and politically pointless sections would have been better left behind.

Interestingly, fingerprinting was always tied up with racism, but never quite as racists hoped. For decades, eugenicists searched for racial patterns within prints; what they found was a total lack of any such distinctions. But following the lead of Herschel in India, white administrators and police who "saw" Asians, Africans and Native Americans as bafflingly homogeneous in appearance fell back on the infinite uniqueness of fingerprints to control the poor, the deviant and the subjugated. And throughout the development of modern identification, people of color have often been the first targeted.

But what does all this mean? Cole, like Hadden, offers massive amounts of research; but like Hadden, he is less than robust in his political analysis. Suspect Identities is just a bit too straight. For example, Cole briefly mentions ruling-class fears of international anarchism during the 1890s as spurring on increased international cooperation among big-city police departments and creation of effective technologies of identification, but doesn't dig deep enough. The fact is, fighting anarchists, reds and labor organizers played a very important part in developing modern forms of identification and police power. Likewise, the control and surveillance of immigrants and people of color have always been tied up with the exploitation of their labor. This larger political-economic context plays too small a role in Cole's overly technical narrative. The result is something of a neutered history that leaves readers feeling as if they are on a hunting trip, only to discover that the gun is loaded with blanks.

To his credit, Cole is very clear and compelling about the implicit racism associated with "biometrics." His last chapter brings the story of fingerprinting full circle with an examination of DNA identification's rapid spread. Like prints almost a century ago, DNA is seen as unlocking biological truth, and in so doing it is reinvigorating both the popularity of biological explanations for behavior and an updated form of eugenics. Political complaints aside, both of these books are empirically robust ventures into important, largely uncharted, historical terrain.