Oooh, I love a good mystery. But sadly, your cross picture seems pretty easy to explain. If you used flash on your camera then the flash would not have extended as far as the 100 feet needed to illuminate whatever it was you were shooting. Secondly, since you had no available light, it's possible your camera used a very slow shutter speed in order to capture as much light as possible. Slow shutter speeds can easily blur or streak a single point light source, thus creating a pattern or cross effect. The 'ghostly faces' at the bottom just look like stray light entering the camera from non fixed locations around you. This stray light only becomes a 'ghostly face' when you consider your location (abandoned prison/boston strangler) and a degree of fear you may have been experiencing at the time.
I believe it was a real ghost.Same thing happened to me at church.And a beam of light was around the person I took the picture of.I took another picture of someone else same day no light.Took another picture of that person the light was around them again.
Wow, cool pics, It's deffinately possible that it was a ghost or spirit. I have heard a lot of stories about this prison being haunted. But like maximus591 says, it could be caused buy your flash and the lack of light available. Personally I believe it was caused by a spirit. Also the blurred picture of the witches residence, I can see an image of a woman in that pic. Thanks for sharing.
Cool pics. I just got back from Salem and actually got my first "ghost orb" photo. Funny thing, I was snapping pics on the night walking tour left and right and nothing. Walking back to the hotel, I was randomly snapping pics as we were walking past the Old Burying Point Cemetery and when we got back to the room, the last pic has the "orb". No one was around us, we were completely alone. It was awesome. I'm a believer.