For eight weeks, M56 moved relentlessly, guided by a primordial compass. He covered more than 100 miles and climbed from sea level to a mile high. He traversed saw-toothed mountains, navigated busy highways and furtively skirted suburban neighborhoods.
The 20-month-old mountain lion, wearing a tracking collar affixed by UC Davis researchers, left his mother in the foothills of Orange County in early March and struck out on his own.
He traveled south through Camp Pendleton, then turned east toward the high country of eastern San Diego County, which opens on the horizon like a centerfold in a coffee table book.
M56 stunned scientists by becoming the first cougar in a decade of study to cross Interstate 15 -- most likely via an underpass where signs point to housing developments that have pushed deep into Southern California's mountain lion habitat. Weeks later, M56 emerged from chaparral-choked wilderness and ducked under Interstate 8 about 45 miles east of San Diego.
Like any juvenile cougar, M56 was searching for food, potential mates and territory unclaimed by another male. Above all, he avoided people. He was learning to survive.
The night of April 24, he moved through a wooded area and stopped a few miles from the Mexican border, just north of Campo. After two months of moving south and east, M56 turned and headed northwest back into the woods.
Maybe it was the light of ranchettes less than a half-mile away. A stray dog might have spooked him. Or maybe he had picked up the scent of another cougar and turned to avoid a fight.
One thing is clear: M56 was about to make his first -- and last -- mistake.
The dogs shattered the silence a couple of hours before dawn. Don and Jaime Dyer awoke and thought the same thing: Coyotes must be trying to get at their sheep.
The Japatul Valley in the mountains of San Diego County is one of countless places in Southern California that is neither rural nor urban. It is country where man and nature coexist uneasily.
Dyers have lived here for 55 years, ever since Don's father traded five acres in El Cajon for 190 acres along a creek a few miles of rugged backcountry from Campo.
Coyotes and stray domestic dogs can be a problem here. Sheep are docile animals and make easy prey if left unprotected at night.
Dyer had built a sheep pen from chain-link fencing he scavenged from the Del Mar Fairgrounds. It was 24 feet square and 5 feet tall -- secure enough to keep coyotes out.
His daughter, Addie, began raising cows and sheep to sell when she was 9. They've won plenty of awards at fairs. More important, the animals have earned Addie about $50,000 through the years, money the 19-year-old is using for college.
When her father reached the pen that morning, he was startled by the grisly scene. Five of Addie's 10 sheep had been slaughtered; the partially eaten carcass of a sixth animal would be found later in the brush about 20 yards away.
"I thought it was one of my dogs," Jaime Dyer said. The family had recently adopted an Akita, a powerful 100-pound hunting dog that wasn't accustomed to being around livestock.
Jaime went back to bed but couldn't sleep. "The thought of the dog doing this made me sick to my stomach."
The next night, the Dyers locked up their dogs and secured their four remaining sheep in the pen. About 1 a.m., they were jolted awake again, this time by their stampeding cattle.
Don Dyer grabbed a .22-caliber rifle. Outside, he found his cows in a circle, facing outward and shielding their calves in the middle. They looked like a wagon train under attack.
Whatever had frightened them was gone. In the pen, Dyer found a lamb and its mother dead. This wasn't the work of a dog.
"I'm about to be out of sheep," he thought. "And my calves will be next."
He stood in the dark holding his slender gun and wondered where the killer had gone. He realized how exposed he was and felt foolish.
"I grabbed the wrong gun," he thought.
Two days before the attacks at the Dyer farm, Winston Vickers was at a county park near Campo speaking at an annual gathering of long-distance hikers about to tackle the Pacific Crest Trail, which stretches from Mexico to Canada through California, Oregon and Washington.
Vickers' topic was his expertise: mountain lion behavior. He didn't know it but M56, one of his subjects, was passing in the forest nearby.
"Like any young dispersing animal, he was searching for territory he could call his own and moving through landscapes he was totally unfamiliar with," said Vickers, a veterinarian and a researcher on the UC Davis Wildlife Health Center's lion tracking project. "What we're looking at is: What decisions do they make time after time?"