On December 2, 1980, four Catholic missionaries from the United States working in El Salvador were raped and murdered by five members of the El Salvador National Guard. The murdered missionaries were Maryknoll Sisters Maura Clarke and Ita Ford, Ursuline Dorothy Kazel, and lay missionary Jean Donovan.

The Maryknoll Sisters, are an institute of Catholic religious sisters founded in the village of Ossining, Westchester County, New York, in 1912, six months after the 1911 creation of the Maryknoll community of missionary brothers and fathers. Until 1954, when they became a pontifical institute, the religious institute was known as the Foreign Mission Sisters of St. Dominic. The sisters use the suffix "M.M." after their names.