When the police arrested him on Saturday, they accused Joseph Rodriguez, a former transit officer, of placing a bomb in the Times Square subway station, causing a blast that injured him minutes after he warned commuters about an impending explosion. That explosion injured an arm, leg and eye.
Mr. Rodriguez, 27, was set to be retired on a psychological disability pension two days after the bomb exploded on July 19. Law enforcement officials have suggested that he wanted a courageous act to cap his four-year career with the force, or keep it from ending.
Mr. Rodriguez's lawyer, Edgar De Leon, said yesterday in an interview that his client is not guilty of the charges of arson, criminal possession of a weapon and reckless endangerment. He refused to address the question of motive.
But if Mr. Rodriguez is found to have built a bomb to create an opportunity for bravery, his case would appear to be an anomaly. While there are no known scientific studies on "hero syndrome" crimes, experts say that police officers are involved in such crimes less often than firefighters and security guards. They also say that it is rare to find a case in which a bomb exploded, injuring the person who allegedly set it.
Jim Wright, a former profiler with the Federal Bureau of Investigation, said that he has not come across a case of a police officer intentionally detonating a bomb for glory in more than 30 years of studying violent offenders. The closest example that he could think of related to an officer - whom Mr. Wright refused to identify, or name the city he served - who was accused of firing a gun at his patrol car's windshield, then claiming that a suspect shot at him.
"I'm not aware of a case similar to the one at hand," said Mr. Wright, a senior analyst with the Threat Assessment Group, a company involved in preventing workplace violence.
Mr. Wright's supervisor, Dr. Park Dietz, a renowned forensic psychiatrist, said that most so-called vanity crimes that are known to experts are committed by security guards. "In a given year," he said, "we see 10 security guard cases; 3 law enforcement cases; 3 firefighter cases, and 4 hospital cases."
The scenarios vary. Dr. Dietz recalled a grocery store security guard who had contaminated produce in order to discover the contamination. There have also been cases of vandalism and of fake bombs made of clay and wires.
Psychiatrists agree that there is no clear profile of a person likely to create havoc in order to help people avoid it. Medical professionals - such as Charles Cullen, the nurse who confessed to killing 16 people while on duty at hospitals in Pennsylvania and New Jersey - tend to act out of a need to feel powerful, psychiatrists say; others do it for fear of losing a job or to exact vengeance.
A 2003 federal study of at least 75 firefighters who have committed arson found that most of them had a simpler reason - because they wanted the excitement of putting out a blaze. The arsonists were usually new to the profession, with about three years experience, and they tended to be volunteers rather than full-time paid employees. They were interested in fire service "for excitement, not for the sake of public service," the report stated.
Michael Rustigan, a criminologist at San Francisco State University, said that most self-created heroes are narcissists in a slump. They are typically people "who are not able to achieve their aspirations," he said. "They've fallen down, and they now want to be heroes." He added, "They are a manifestation of our culture's obsession with fame."
Dr. Alfredo Nudman, head of the personality disorder unit at Weill Cornell Center of New York-Presbyterian Hospital, said that public, self-created acts of bravery have often been the result of earlier claims to greatness.
"They go around boasting about themselves and brag about what they do," he said. "Then people start to notice that they're a fake, so they have to up the ante to be recognized."