A survey of approximately 5,000 Americans ages 60 and older, which questioned them about their experiences of abuse in the previous year as well as their lifetimes, found that 1.6 percent had experienced physical mistreatment. Of this group, only 31 percent had reported their abuse to police. Strangers accounted for only 3 percent of these assaults; family members perpetrated 76 percent of the cases. Among those surveyed, 0.6 percent reported being sexually abused in the previous year, and approximately 16 percent of the victims said they had reported the assault to the police. Family members were responsible for about half of the assaults. Other types of abuse included financial exploitation (5.2 percent), potential neglect (5.1 percent), and emotional abuse (5.1 percent). Another study found that bruises that were inflicted on victims in confirmed incidents of the physical abuse of elderly victims differed in characteristics and locations on the body compared to bruises that occurred accidentally. Abusive bruises were often larger, with more than half being 2 inches in diameter or larger. Physically abused elders were also more likely to have bruises on the head and neck, (especially the face) as well as on the posterior torso. Regarding factors in the successful prosecution of elder abuse cases, The U.S. Attorney's Office of the District of Columbia has worked effectively with victim-witness advocates in elder abuse cases. Victim-witness advocates have performed tasks that range from trial preparation to helping victims find new housing.