Tests results show that a wolf that bit a 16-year-old boy's head at a northern Minnesota campground had severe deformities as well as brain damage, which likely explains the reason for the "unprecedented" freak attack, wildlife specialists said Thursday.

DNA tests results also confirmed that the gray wolf that was trapped and killed two days after the late-night attack is in fact the same wolf that bit the teen. The wolf tested negative for rabies.

All of that is a relief for the family of Noah Graham, the Solway, Minn., teen who was bit last month while lying on the ground, but not inside a tent, at a Chippewa National Forest campground near Lake Winnibigoshish. "We all felt 98 percent sure that was the animal," Noah's father, Scott Graham, said Thursday after Department of Natural Resources officials called him with the test results. "My concern was that the wolf was diseased and Noah could contract something. But that wasn't the case."

The rare encounter last month was Minnesota's first documented wild wolf attack on a human that resulted in a significant injury.

The day before the attack, the wolf had been seen in and around the campground, said Dan Stark, the DNR's large carnivore specialist. "It bit into a tent. Punctured an air mattress. It was standing on a picnic table — things you wouldn't expect a wild wolf to do. He was never aggressive, and he never approached anybody.

"So why did it bite somebody? Whether it actually knew what it was biting into is probably unlikely. It was biting something on the ground, and it happened to bite into somebody's head," Stark said.

Results from the wolf necropsy conducted by the University of Minnesota Veterinary Diagnostic Laboratory show the wolf, estimated to be 1½ years old, suffered from a severe facial deformity, dental abnormalities and brain damage caused by infection. Anibal Armien, university pathologist and veterinarian, said it's likely the wolf experienced a traumatic injury as a pup and those injuries developed into abnormalities that caused the brain damage.

Those deformities and abnormalities likely hampered its ability to effectively capture wild prey, said Michelle Carstensen, DNR wildlife health program supervisor. The wolf's stomach contained only fish spines and scales.

The wolf's problems also likely predisposed it to be less wary of people and human activities than what's normally observed in healthy wild wolves, Carstensen said.

That "strongly explains" why the animal was behaving the way it was and why it was searching for food around the campground, Stark said. "It's surprising that a wolf in this condition survived to this point given its reduced ability to survive in the wild."

Attacking a human is "definitely abnormal and unusual," Stark said. "Occasionally … we get nuisance complaints of wolves in people's yards and interactions with pets, but rarely is there any aggression toward people. This kind of thing is unprecedented."

Stark said there have been two other attacks by wolves in Minnesota but neither resulted in injury. One happened to a logger in the 1970s, and the other was to a rabbit hunter a decade later.

The Solway teen suffered multiple puncture wounds and a laceration to his head that required staples. He also received rabies shots.

"He's pretty healed up," his father said while walking through the woods partridge hunting with his two young daughters. "I don't think [the attack] is going to curb any of our camping or hunting."

But Noah Graham may find himself looking over his shoulder every now and then when he walks in the woods, his father said.

The teen often walked through the woods in the early morning darkness to his deer stand. "He never used a flashlight," his father said. "But I don't think he'll do that anymore. He'll probably use a flashlight."

Mary Lynn Smith • 612-673-4788