Complex sentence: From the mid- 1880s on Rebecca Salome Foster was known as a "Tombs Angel" because she attended to female criminals incarcerated at The New York Halls of Justice and House of Detention.
Split into simpler sentences: From the mid- 1880s on Rebecca Salome Foster worked assisting people were defendants in the New York legal system. She became known as a "Tombs Angel" because she attended to criminals incarcerated at The New York Halls of Justice and House of Detention.