This is a Hollywood mystery, sad and violent, about longing and loss and a murder most foul on Mulholland Drive in the hills of Malibu, where the pretty and the rich live among the coastal oaks and sage chaparral and bounding deer, a place where the wild things are.

The perp? He is a loner and a wanderer and a meat-eater, we know that, and he is still on the loose. He sleeps during the day, moves at night, dashing across twisted roadways, rarely spotted in the headlights of a careening Hummer. Even before the incident, he was a celebrity, if a reluctant one.

Yes, they made a National Geographic documentary about his life, but it wasn't like he posed for the camera. The investigators have been tracking his movements for years, though very few people have ever seen him. Maybe he's got a mean streak in him, or was just acting out his nature. Perhaps he feels trapped. The authorities aren't sure. They respect him, even if they don't understand him.

And the victim? She was smaller than his 150 pounds, younger, less experienced, more of a homebody, but obviously a fighter, a real wildcat at the end. She was his mate, willing or not, and the mother of his offspring, the quadruplets, two sons and two daughters, just a year old and now vulnerable and on their own.

He killed her in front of them, in front of the young ones.

And he took his time.

There's still a lot the officials don't know, but sometime on the morning of Aug. 12, a Friday, a wildlife biologist with the National Park Service named Jeff Sikich was tracking Puma-1, the big male, out in the Santa Monica Mountains National Recreation Area, 250 square miles of rugged wilderness surrounded by the second largest metropolis in the nation. They were trying to recapture P-1 to change his radio collar, since he and Puma-2, the female (the recently deceased), might have been the last adult mountain lions, Felis concolor, living in the Santa Monica Mountains -- stuck in a box bounded by the Pacific Ocean, Brentwood, the farm fields of Oxnard and, most troublesome, 10 lanes of hurtling traffic on the Ventura Freeway.

When Sikich arrived at the scene, near Malibu Creek State Park off Mulholland, there were radio signals from P-1 and P-2 and the kittens, which had tracking device implants. Seth Riley, a wildlife ecologist with the National Park Service, says that P-2 was in her home range with the cubs and that P-1 had recently made a beeline for her from 15 miles away, where he'd been hunting near Topanga Creek, just this side of Sunset Boulevard. "Maybe it was the scent of the young males or the female adult," Riley says, that brought him running. Maybe P-2 was in heat again.

What Sikich heard could give a Malibu real estate agent nightmares. "It was incredibly loud and scary sounding," says Riley, who listened to the sounds via a cell phone that Sikich held up to the noise. "We thought they were fighting. But one thing about cats is they can also make a racket when they're mating." The screams -- lord -- went on and on. The biologists backed off.

On Saturday, they began detecting a "mortality signal" from P-2's radio collar, meaning that she had not moved for eight hours. The cubs were still close. On Sunday, the scientists found P-2 "lying on her back with her head at a weird angle, marks on her skull, puncture wounds," says Riley. They carried her off, first to the freezer and then for an autopsy. The verdict: "He grabbed her by the face, and I guess he basically killed her," Riley says. The female also had bruises and wounds on her legs. Meaning she fought and he fought and he won.

Why? Real estate, people. Supply and demand is red in tooth and claw.

Initial reports suggested that the pair may have fought over a deer killed by P-2, but the scientists couldn't find a carcass. Riley's best theory: "She fought defending her kittens." He and his team consulted with lion experts in the West and found cases where younger females have died while mating with more powerful males. "It would be unusual that he would kill a female he had mated with, but it is not unusual for a male to kill a female with kits or to kill young males."

P-1 may have gone after his sons. At about a year old, they're teenagers in human terms, and we know what teenagers are capable of. P-1 may have concluded that the Santa Monica Mountains were not big enough for more than one alpha male. In a more natural setting, his sons may have already dispersed to new territories (while females often stick closer to the natal ranges).

But this is the tough part, and it breaks your heart, if you care about stuff like this. The remaining lions of the Santa Monica Mountains may be stuck with each other, like a family out of some Eugene O'Neill play. To move north into the Simi Hills toward the Ronald Reagan library (an area where two other radio-collared lions, P-3 and P-4, died last year after eating rat poison), a lion would have to cross the Ventura Freeway, which flows like a ceaseless river of traffic all day and most of the night. And then to get from the Simi Hills north again to the Los Padres National Forest, where a population of lions thrives, a big cat would have to cross two more busy freeways.

If they're trapped, it is possible that over time P-1 will hunt down and kill his sons and then mate with his daughters. Which can play havoc with the gene pool. Unless. Unless the lions can find a way out -- or a way in.

Ray Sauvajot, science director for the National Park Service in the Santa Monica Mountains, says researchers could be surprised. "We could have more lions out there that we don't know about. And they do move around," he says. Last year, a lion was reported in Griffith Park near downtown Los Angeles, but the sightings were never confirmed with paw prints or deer carcasses or big-cat droppings, so the biologists remain skeptical.

For years, California officials have been debating plans on paper to connect the Santa Monica Mountains to the Simi Hills to the Santa Susana Mountains by constructing wildlife corridors (probably culverts or tunnels) to let the lions and other top-end predators -- bobcats and coyotes -- move around the major freeways. So far, though, none has been built.

Puma-1 is still out there. One thing that has amazed researchers over the years is that the lion apparently is living off deer and other natural prey, and not the poodles of Pacific Palisades. Nobody sees him. He's not hurting anybody, except those closest to him.

The female mountain lion known as Puma-2 was living in the Santa Monica Mountains.The male mountain lion known as Puma-1, below, and one of his cubs, above. Wildlife biologists with the National Park Service says P-1 killed his mate, Puma-2, in August in front of their four cubs, who were not harmed.

Park Service biologist Jeff Sikich with a cub when it was only a few months old. Sikich was tracking Puma-1 when the killing occurred.