It is not unusual to have a case that continues far beyond the scope of a preliminary investigation. If the evidence that is found during the initial investigation proves promising, the team may return again and again to gather evidence.

A prerequisite, of course, is that the haunting is not causing problems for the client and that he has decided he can live with the situation. When people understand that the ghost(s) are not trying to harm anyone, they often accept the situation and decide to peacefully coexist. This allows investigators the opportunity to delve deeper into the case and gather more evidence.

The Paine House Museum in Coventry, Rhode Island, is an ongoing investigation site for T.R.I.P.R.G. They have returned repeatedly, and even though one of the entities present has caused some distress to the sensitives, they find the site to be too active to leave alone.

This is often the case for paranormal investigators. Some cases are so active that the team can barely scratch the surface in just one visit, and it may be possible to do an investigation that stretches out over the course of days. If the site is secure the investigators have the added advantage of leaving the equipment set up and in place.

Repeat Offenders

Another reason to follow up on a case may be that the entity that was bothering the client has returned. When this happens, the team has to return to the site and try to evaluate the situation. Is it really the site that is haunted, or is it the people? This has to be determined first and may take a great deal of work to uncover. Sometimes it is clear that the client has personal issues that are far graver than dealing with a few ectoplasmic entities.

If a client believes she has been the victim of a demonic oppression, she may very well be emotionally and physically exhausted and should be referred for appropriate follow-up treatment by mental health practitioners. Investigations can continue while this is going on, but extreme caution and consultation with a demonologist or person who deals with malevolent entities regularly is highly recommended.

Some of the most spectacular evidence of paranormal activity has been witnessed during this type of case, but the well-being of the client should always take precedence over evidence gathering. The safety of the team also comes into play during this type of case.

Hard Evidence

Sometimes the team may return to a site that was promising at first but that produced no hard evidence. If a team refuses to use any sort of metaphysics to document paranormal activity, or even an investigator's own personal experience, they will need to return to gather evidence that can be verified through technological documentation. Although some think modern ghost hunting relies too much on science and prefer the experiences of sensitives and psychics, many groups now stick to the hard-evidence protocols.

What are these ways of gathering hard evidence? They usually coincide with other methods of evidence gathering, such as photography or digital videotaping. But they can also mean the use of more instruments, such as mobile weather stations, which are used so that data such as humidity and air movement can be recorded. They can also identify potentially ordinary explanations for reports of activity, such as drafty windows and old radiators.

Ruling Out Natural Causes

Infrasound is low-frequency sound, and although it is audible to the human ear, it may not register on a conscious level. It can sometimes cause people to believe they are seeing things out of the corners of their eyes, or to experience the creepy sensation of being watched. Infrasonic sound is now believed to be one possible explanation for why some people experience quickly moving shadows as a haunting.

Small motors produce these sound waves, which resonate around eighteen or nineteen cycles per second. The human eyeball has a resonance frequency of eighteen cycles a second, so the theory goes that the sound wave produced by the motor sets up a sympathetic resonance in the eye, triggering the impression of fleeting images.