Many North American cases exist. Slain animals had no blood, bore signs of laser surgery and some organs were removed. UFOs, black helicopters and others were blamed.

Sheep, horses and humans have also been mutilated. Many cattle were found marked with fluorescent paint. The cause of death was undetermined, their blood, drained and precise laser surgery marks, discovered. Some organs had been removed. Abnormally high radiation levels were found near the corpses. Scavengers wouldn't touch carcasses. Animals were taken from their habitats and mutilated elsewhere. Sightings of UFOs and strange unmarked black helicopters coincided with many mutilation cases.

Evidence

Marks found on the animals weren't consistent with attacks by known predators. In many cases, owners heard nothing at the time of the mutilation, usually done at night. All organ removals and incisions were done with surgical precision. In some cases the evidence of cauterization along incision lines, indicated a laser was used. Bones were clearly cut leaving no fragments. Animals' bodies were drained of blood, but no trace of blood is found, no signs of a struggle, footprints or tire tracks found near the corpses. Typical mutilations showed huge oval shaped incisions around the jaw bone. In most cases jaws and tongues were removed. There is no consensus that the phenomenon actually exists, or if it does exist, what causes it.

Theories

Postulations are divided as to the nature and causes of this phenomenon.Some say there are no mysteries about the deaths and people misinterpreted normal ones, but this remains an unexplained phenomenon. Believers respond that many debunkers have little or no field experience with this phenomenon. Farmers and veterinarians made distinctions between normal predation and the mutilations.
  • Skeptics: They believe the deaths were caused by natural causes, then were eaten by a variety of scavengers, such as birds, animals and/or flies. They tend to eat the eyes and softer internal organs. The absence of the mouth, lips and genitalia could be due to dehydration. Blood settles to the lowest bodily point, breaking down into its basic chemical components, accounting for the lack of blood.
  • Ufologists: This theory rests on the fact that UFOs have been sighted in the area when the mutilations happened. Some accounts included seeing the animal being lifted off of the ground. UFOs exist in the paranormal realm.
  • Black helicopters: It's alleged that humans came out from what appeared to be a UFO. When its cockpit lights were lit, they revealed helicopter rotors above the craft. Expansion of this theory is that the systematic removal of some bodily parts was a covert test for chemical or radioactive contamination. A large amount of mutilations happened near former nuclear test sites. Speculation is that the U.S. Military dissected animals to examine the amount of exposure they receive from radiation fallout. Ranchers organized armed patrols with the intention of firing at the helicopters if the chance presented itself. If true, we may never know the truth because the government has been covering up information for decades, as evidenced by the Tuskegee experiment and MK-Ultra.
  • Mothman and Chupacabra: John Keel, an expert in Mothman and writer, claims to have examined a number of slain animals in the Point Pleasant, West Virginia region. They had disfigurements found in the Midwest ones. Some blamed Chupacabras. Both are cryptids whose existences aren't scientifically proved.
  • Cultists: Some speculated that the mutilations may have been perpetrated by satanists or other cultists. Allegedly, they're sacrificed to Satan. They're either hoisted on extendable cranes or lowered from helicopters.
FBI Investigation

The Animal Mutilation Project, conducted y the FBI contains accounts of mutilations reported during the late 1970's. The agency became involved when fifteen happened in New Mexico. Various theories were explored, including natural predators, UFOs, satanic cults, and pranksters. It failed to identify what was responsible.