It is usually those who die tragically, suddenly or by the hand of another, who remain attached to the earth plane, there is possibly unfinished business or an intense tie to people or a place. Spirits remain earthbound for various reasons, some only for a short period of times, others for longer, some remaining for centuries leading to the tales of haunting we hear about. On occasion a spirit feels compelled to pass on a message, and through the assistance of a well-schooled medium they manage to do this, they are then at peace, having moved into the light and eternal rest or to await their reincarnation.
Fear of the unknown and individual fear-based belief systems may cause a spirit to remain earthbound, these spirits tend to remain between the earth and the next realm until their fears subside or are released completely. Others stay because they are worried about their families and the affect their death will have on them. Sometimes the living can interfere with the dead’s ability to pass over, especially if they are unable to let go and think about the person all the time. Maybe even going to the extreme of constantly trying to contact them hoping to hold onto them, once they accept that their loved one is gone the spirit is then released and readily crosses over.