The Bangs Sisters - Chicago's spiritualist portrait painters

Mary "May" Bangs (born 1864) and Elizabeth "Lizzie" Snow Bangs (born in 1860) were mediums, getting publicity for contacting the dead at a very early age, with written reports of their seances dating at least as early as 1872.  Eventually the duo would become famous for materializing painted portraits of the dead.

 From the Wikipedia entry on the Bangs Sisters

The pair gained quite a following, with patrons regularly attending seances at their home in Chicago.  They also were the subject of numerous venomous newspaper articles and police raids - in 1888 one raid resulted in the death of Lizzie's 7 year old daughter.  After this incident, the sisters released this card:

 

Even marriage was scandalous for the Bangs sisters.

There was a lot of speculation regarding the method employed in the creation of the portraits of the dead.  Many believed that they were painted over enlarged photographs and/or painted by students hired from the Art Institute.

Video showing many of the Bangs Sisters' "precipitated" portraits, with some notes about the supernatural nature of the paintings themselves.