In 1922 the community of Caldonia Mills, NS (Antigonish) was stirred by reports of strange manifestations, rappings, spontaneous fires, and other "ghostly" events. The stories led to a Doctor Prince arriving on the island to investigate.
Dr. Whittier F. Prince was a member of the American Society of Psychic Research in New York City. Very shortly, however, he was claiming that the girl was the exact same person whom he had investigated some nine years prior in Missoula, Montana when she was nine years old. Raps, bangs, and other manifestations had occurred when Mary Ellen was in a sleep walking type state and Dr. Prince termed it "self-hypnosis".
An examination of the 1910 US Census revealed that there was only one "Alex MacDonald" in Montana, aged 20 born in Scotland - so Dr. Prince's claim may be false. To invalidate Prince's claim proof of her whereabouts in 1912 would be needed (census, etc.). Remember too, that Mary Ellen was reported to be 16 at the time of the NS events. A 1922 photo reveals a stocky, mature looking Mary Ellen, as tall as her foster father.
The family in NS said they had never been off the island. The story was picked up by the New York Times, and dozens of other papers across North America. Many others investigated the stories and finally "Mary Ellen Spook" as the woman came to be labeled, moved to central Canada. There were reportedly no further occurances after the island.
To learn more: http://www.parl.ns.ca/maryellenspook/article2.asp and http://www.townofantigonish.ca/folklore.html
Another NY Times article from 1922 recounts the puzzlement of the Dr. Prince about the whole situation and how it was confounding his ability to solve the problem:
Unanswered questions do remain: Who was Dr. Prince and why was he called in? What is the truth behind the tales of demonic black dogs, mysterious fires, and the like? Who was the family Prince mentions from Missoula, Montana? What do they have to say about the visit of the good Dr. Prince? Did the episodes really stop once she moved away? Who were her birth parents and did those children exhibit any similar manifestations? Was this all the pranks of a bored farmer, or bored young woman seeking excitement? Or, was this a rare experience of some form of special kenetic ability as of yet unexplored?