The mentalist, mindbinder, and author of Haunted Providence delves into the 19th-century murder of Sarah Maria Cornell.   "If I should be missing, enquire of the Rev. Mr. Avery of Bristol, he will know where I am."   This scribbled note belonged to Sarah M. Cornell, written the day her body was found hanged in a rural pasture in Tiverton, Rhode Island. An unmarried young woman of limited means, Sarah was four months pregnant, and a married Methodist minister stood accused as the father. Local authorities grew skeptical of Sarah's apparent suicide as Reverend Avery's conduct appeared increasingly suspect, and eventually the extensive evidence of their tortured relationship set off a groundswell of public interest and media attention never before seen in 1830s New England. This tragic crime left the nation clamoring for justice and became one of early America's most sensational murder trials.