â€œStudents of assassination in the U.S. have generally seen assassins and attackers of political leaders either as possessing â€˜politicalâ€™ motives or as being â€˜deranged,â€™â€ notes a 1999 comprehensive study [PDF] of the 83 known and would-be attackers in modern American history. â€œThis is a narrow and inaccurate view of assassination."

â€œThere is no profile of an American assassin,â€ forensic psychologist Robert Fein and his co-author Bryan Vossekuil, former head of the Secret Serviceâ€™s National Threat Assessment Center, emphasize. But the Tucson attacker, Jared Loughner, is pretty typical. Of the 83 attackers analyzed, 71 were male, 63 were white, 41 had never married, 47 had no children, about half had some college education, and about half were unemployed at the time of their attacks. â€œAlmost all subjects had histories of grievances and resentments,â€ note Fein and Vossekuil.

Politics apparently plays very little role in most attacks and would-be attacks against public officials. The researchers found that â€œfewer than a tenth of subjects who acted alone were involved with militant or radical organizations at the time of their attack or near-lethal approach.â€ Instead, they seek notoriety, revenge for perceived wrongs, death at the hands of law enforcement, to bring attention to a perceived problem, to save the country or the world, to achieve a special relationship with the target, to make money, or to bring about political change. Less than a quarter of the attackers developed escape plans. In fact, more than a third wished or expected to die during their attack.

However, â€œmore than a fourth had a history of interest in militant or radical organizations and beliefs.â€ For example, radical leftwing ideology motivated presidential attackers like Lee Harvey Oswald and Sara Jane Moore, while rightwing views inspired members of The Order to kill liberal radio talk show host Alan Berg. Though Loughner has a digital trail of a weird assortment of fringey views, none of them seems to have motivated the attack.

Moreover, diagnosed mental illness is not a good indicator of who might become an assassin. Fein and Vossekuil find that â€œfewer than half of American assassins, attackers, and near-lethal approachers since 1949 who chose public officials or figures as their primary targets exhibited symptoms of mental illness at the time of their attacks or near-lethal approaches.â€ Not surprisingly, the more mentally disorganized an attacker, the less likely their attack was to succeed.

The researchers note that 46 of the attackers and would-be attackers in their study had been evaluated by a mental health professional at some point in their lives, but only 16 had been treated for mental health problems in the year prior to their attacks. They acknowledge that a greater percentage of attackers have been mentally ill than have been members of the general public, but warn that â€œit is a mistake to automatically assume…that focus on the presence or absence of mental illness is critical to determining the risk of violence to a public official or figure that a given individual may pose.â€

Fein and Vossekuil report that 31 of the attackers had experienced an episode of serious depression and 29 had threatened to commit suicide at some point in their lives. In addition, in the year before their attacks, half of them had experienced a major loss or life change including marital problems, personal illness, death of a family member, or failure at school or work.

Recent news reports strongly suggest that Loughner was experiencing some form of mental illness, but he was sufficiently organized to plan and carry out the attack. Loughnerâ€™s defense lawyer may well attempt to argue mental illness as a defense. Fein and Vossekuil, however, observe that of the previous attackers who went to trial only John Hinckley, would-be assassin of President Ronald Reagan, was found to lack criminal responsibility by reason of mental illness. (Hinckley was trying to impress actress Jodie Foster.) To the extent the public gets to hear from Loughner it will likely turn out that he was chiefly seeking notoriety and possibly death, rather than reacting to supposedly vitriolic political rhetoric.

Most interestingly, the researchers found that â€œno assassin or attacker communicated a direct threat about their target to the target or to a law enforcement agency before their attack or near-lethal approach (emphasis theirs).â€ Consequently, they assert, â€œThe idea that the persons who pose the greatest risks to public officials and public figures are those who make explicit threats is a myth.â€ On the other hand, those who do attack often hint to associates or family members about their plans. In addition, perpetrators frequently keep diaries or notes outlining their intentions.

A 2004 review article [PDF] of studies dealing with threats and attacks reported that research evaluating a selection of threatening letters sent to members of Congress found that â€œthe presence of any threat in a letter was associated with a lower risk of approach.â€ In other words: Big talk means no action. In addition, the review found that people who made contact with and later approached members of Congress were predominantly engaged in â€œhelp seekingâ€ that â€œinvolved personal issues, rather than ideological ones.â€

In light of these findings, Jared Loughner, perpetrator of the horrific Tucson massacre and would-be assassin of Rep. Gabrielle Giffords (D-Ariz.), is pretty much the usual suspect when it comes to attacks on public officials. He is an unmarried, childless, unemployed white male with no readily discernible political motivations who just experienced a major life failure when he was kicked out of community college. At this point Loughner does not appear to have been associated with any political organization. Investigators have apparently found an envelope in a safe at Loughnerâ€™s house inscribed with the words, â€œmy assassination.â€ While Loughner had previous contact with Giffords at a public meeting in 2007, as far as is currently known, he made no direct threats against the congresswoman.

Fein and Vossekuil report that there were only five attacks against members of Congress between 1949 and 1996. (Presumably this includes the 1954 incident in which a group of Puerto Rican nationalists shot five congressmen from the House gallery, all of whom lived.) The attack on Giffords increases the number of incidents to six. In the modern era, only two members of Congress have been assassinated, Sen. Robert Kennedy (D-N.Y.) when he was seeking the Democratic presidential nomination in 1968, and Rep. Leo Ryan (D-Calif.) in 1978 when he was visiting the Jonestown religious cult in Guyana. Fein and Vossekuil report that there were only four attacks against federal judges between 1949 and 1996. Only one federal judge was killed between 1789 and 1979, while three were killed between 1979 and 1989. Now the murder of Judge John Roll during the Tucson massacre must be added to the list. The attack on Giffords increases the number of incidents to six.

Finally, attacking any innocent person is abhorrent and the perpetrators must be severely punished. In my opinion, the relatively few attacks on public officials (fewer than 80 in 60 years with about a third of those aimed at the president) provide no real justification for erecting the modern massive security infrastructure in which government officials and buildings are being increasingly closed off to citizens. I admire Rep. Giffords' willingness to meet and talk with citizens where they live. I hope for her speedy recovery.

Ronald Bailey is Reason's science correspondent. His book Liberation Biology: The Scientific and Moral Case for the Biotech Revolution is now available from Prometheus Books.