Plus, that is not something a seller would be required by law to disclose as I believe it would be hard to prove.
Remember.....Who do you want to call....."Ghost Busters!"
Think about it. Does it matter if the ghost were there last year, or in 1892? No.
I recommend the services of a good clairvoyant, or other-side-seer. I do not know of any in your area. But if you inquire around and ask some prominent local psychics, they may be able to lead you to a good expert.
Again, the key is whether the ghosts are there now, not in the past.