I've just found out that Ann Alcock Foster is my 9th great grandmother and if you're a member of Ancestry.com you can do a search on her and find the book "Historical Sketches of Andover" which has a whole chapter on the Witchcraft in Andover and quite a lot about Ann Foster and her daughter and granddaughter, Mary Sr. & Mary Jr. Lacey. You can also look at http://etext.virginia.edu/salem/witchcraft/ for some more good info, trial transcripts, and maps and things. There seems to be a real lot out there to look at.