The panelists were Jacquelyn C. Campbell of Johns Hopkins University, author David Adams, and Richard Gelles of the University of Pennsylvania. Campbell discussed the Centers for Disease Control and Prevention's National Violent Death Reporting System. Of the 408 homicide-suicide cases, most perpetrators were men (91 percent), and most used a gun (88 percent). Campbell's 12-city study of these cases found that the greatest risk factor was prior domestic violence (70 percent of the cases). Other risk factors were perpetrator's access to a gun, threats with a weapon, a stepchild in the home, and unemployment when combined with a history of domestic violence. Adams offered his perspective based on years of research and experience in working with domestic violence cases. His comments focused on guns and jealousy as factors in these domestic violence cases. He noted that compared with the considerably lower rates of intimate-partner homicide in other wealthy countries, the United States has the most permissive gun laws of any industrialized nation. He made a similar comparison among U.S. States that have restrictive versus permissive gun laws and lower versus higher homicide and suicide rates. According to Adams, a jealous substance abuser with a gun poses a particularly deadly combination of factors. Gelles reported that 90 percent of the time, the best predictor of domestic violence is past behavior. One particular type of behavior identified by Gelles is "overenmeshment," which is a condition in which perpetrators either view "their family members as possessions that they control or they don't see any boundaries between their identity, their wife, and their children."