The most accurate crime statistics are on murders. When proponents of infringements on the Second Amendment talk about murders, they often claim that murders by strangers are only a small percentage of the total, often about one quarter. This statistic is misleading, because it implies that people that you are close to are the most likely to murder you.
The largest category of victim to murderer is unknown. That is 44 percent of the murders reported to the FBI. The next largest category is acquaintance. It is 21 percent of murderers. The misleading part is that all people who you know, no matter how slightly, that are not close to you, are put in this category. Thus, the gang banger that was in your remedial English class, the people in your exercise class, the laborer who cleaned up the neighbor's back yard, the drug dealer that you told the police about, are all non-strangers, as are all of a gang members gang, criminals that other criminals knew in prison, and drug dealers customers and competitors. The third largest category are strangers, at 12.4 percent. 12.4 percent of the total murderers are 22 percent of the murders where the victim/murderer relationship is known, so that is where the "only one fourth of murderers are strangers" comes from. Add the top three categories, unknown, acquaintances, and strangers, and you have 77.5 percent of murderers who are not in the "close to you" categories.
It may be that some of the unknowns are people that were close to the victim, but have escaped prosecution. Some may be simply sloppy reporting. But to imply that they are in the same proportions as the known relationships is misleading, as is lumping in immediate family with acquaintances.
The other side of this misleading statistic is that violent, bad people have family and friends as well. Divorced women have angry exes. Many families have their black sheep. Some children develop drug habits and victimize their parents. All of those fit in the category where the murderer was in the immediate family.
The next time that someone tells you that most people are murdered by family and friends, so a gun in the house is more danger than deterrent, tell them that less than one eighth of murderers are immediate family members, and that unknown, strangers, and acquantances make up more than 75% of murderers.