O.J. Simpson case helped bring spousal abuse out of shadows

In a letter that surfaced after her 1994 death, Nicole Brown Simpson detailed the violence that framed her marriage to O.J. Simpson.

In the 25 years since then, spousal abuse has moved from a private matter to a public health concern. Crisis hotlines in the U.S. receive 20,000 calls a year about domestic violence, and police and advocates work together more often. But the number of fatal attacks is climbing, with four people killed each day.

Rachel Louise Snyder is a professor at American University and author of a new book titled "No Visible Bruises: What We Don't Know About Domestic Violence Can Kill Us." She says Simpson's death emphasized a conversation that advocates had been having for years — "that it could happen anywhere, to anyone."