Long ago, when cattle mutilations became a thing, one of the epicenters of this, New Mexico, hired an ex-FBI agent , Kenneth Rommel, to investigate and report on what was going on. His report was published, and I ordered a copy. It was very mundane. Careless small ranchers and farmers lost cattle to natural causes. Often brucellosus. Scavengers took advantage of an easy meal. Usually they went for soft parts of the carcass. These bodies would initially swell up. Buzzard beaks are good at cutting into flesh. As the swelling went down over time, the bites were less jagged looking. The surgical precision of the irresponsible media reports was much exaggerated. No blood? After a few days, blood settles in the lower part of the carcass and coagulates. The sensationalists decared it could not be the work of buzzards, No way! But the buzzard poop on the carcasses was a dead give away. Other scavengers included coyotes and dogs. Some ranchers remarked how odd it was their dogs never barked. Rommell noted it is hard to bark when your mouth is full of meat. A few local deputies ignored all evidenced and spread disinformation to sensationalist press and UFO kooks. And a good conspiracy story never dies. And creates a template for more of the same.
The mystery of the cattle mutilations is solved by animal forsenic tests, usually not done or ignored, and ignoring such dead give aways such as buzzard and coyote poop in the vacinity of the mysteriously dead cow carcass, and in the case of buzzard poop, often on the car ass itself.
Kenneth Rommel at last report is still alive and occasionally seems to get interviewed. I could not find Rommel's report on line, but I did no do a really thorough search.