Jennifer Sanmarco, a 44-year-old former U.S. Postal Service employee, entered a mail distribution center in Goleta, Calif., late Jan. 30 and opened fire with a 9 mm semiautomatic pistol, killing five postal workers before taking her own life. Although this latest example of workplace violence features many of the usual characteristics of such attacks, it is unusual in that the alleged shooter was a woman. It also was the most violent workplace attack by a woman to date. According to local postal officials, Sanmarco had worked at the distribution center, located about 100 miles north of Los Angeles, for six years before being placed on medical leave in 2003 for psychological reasons following an incident that ended with her forcible eviction from the facility by local sheriff's deputies. During that incident, Sanmarco reportedly made no specific threats to others, but there were concerns that she might try to hurt herself. Other employees, in fact, had noticed that her behavior had grown increasingly erratic after a relationship with a co-worker ended. After losing her job, she moved to New Mexico, where her pattern of erratic behavior reportedly continued. While employed at the post office, Sanmarco displayed many of the warning signs that can lead to workplace violence. Because of its experience with such violence, the U.S. Postal Service is sensitive to these situations, and the local center had taken the necessary precautions by placing her on leave in 2003. The case, however, is an example of how ex-employees, those familiar with security measures at their former jobs, can override efforts to keep the workplace safe. Sanmarco's knowledge of the facility's layout, security measures and shift schedule enabled her to defeat two layers of protection. She gained access to the center during the 9 p.m. shift change by closely following another car through the facility's gate before it closed. While in the parking lot Sanmarco shot three employees, then took an employee's access card at gunpoint to gain access to the building itself. Once inside, she began confronting employees where she found them, shooting three other employees before turning the pistol on herself. Sanmarco reportedly reloaded her pistol at least once while inside, indicating that she had expended all of her ammunition, but wanted to continue her spree. It is unclear whether Sanmarco had specific employees in mind when she began her killing spree, but she did know her victims and they knew her. According to reports, all of the victims except for one were shot in the head — a very specific and deliberate way to kill. The shooting spree also occurred during the overnight shift, the same shift that Sanmarco worked while employed at the distribution center, suggesting she would have known which employees would be present at the time of the attack. The shooting spree might have been the culmination of a night of violence. After the Goleta attack, Santa Barbara County Sheriff's Department deputies found the body of a woman who was a former neighbor of Sanmarco at a condominium complex. The woman had also been shot in the head. The incident is unusual in that the shooter was female, and that the body count was high for a female shooter. In the vast majority of workplace violence incidents, the shooter is male. Although women have committed such acts, the death tolls tend to be lower. In the weeks after widely publicized incidents of workplace violence, copycat killings usually occur. Because the shooter in this case was a woman, females could be the copycats.