The mountain lion did not commit the perfect crime.
DNA evidence left behind in a San Mateo County home confirms that it was a big cat that snatched a woman's little dog last week.
The incident happened at about 3 a.m. April 17 as the woman and her child slept in her bedroom. The woman's 15-pound Portuguese Podengo suddenly started barking.
The woman woke up and saw a shadow of an animal, which walked through her partially open French doors and entered her bedroom, according to Det. Salvador Zuno, spokesman for the San Mateo County Sheriff's Office.
The animal then took the small dog from the foot of her bed and walked out, he said.
The woman used a flashlight to look for her dog, but saw only large wet paw prints at the entrance of her bedroom.
A wildlife officer who responded to the scene was unable to find "any other tracks or obvious sign of a mountain lion," the agency said in a statement.
But the officer did discover a small drop of blood on the door of the home in Pescadero that he collected for analysis.
The blood sample was taken to a wildlife forensics laboratory in Sacramento that same day.
On Monday, the California Department of Fish and Wildlife confirmed what was already strongly suspected: The killer that slunk away with the dog in the early morning darkness was a mountain lion.
"Forensic analysis confirmed the blood found in the home was predominantly domestic dog, with trace amounts of mountain lion DNA," the agency said.
The property owners are eligible for a permit that would allow them or someone acting on their behalf to hunt and kill the mountain lion.
But they opted not to pursue the permit, being satisfied that they were within their legal right to dispatch the lion if it returned, said Capt. Patrick Foy of the Department of Fish and Wildlife.
Foy said the department could take on that responsibility if there was any indication that a mountain lion was a direct threat to people. But he said all indications suggested the small dog was its intended prey.
Foy said mountain lions see small animals and even larger ones like sheep, goats and lamas as prey. Even horses have been attacked, though it's more rare because of their size, he said.
But Foy said a mountain lion walking into a home was a new one for him.
"I can't personally recall a mountain lion entering somebody's home," Foy said. "This person had left the door open, so the animal got in. That problem is fixed. They're not sleeping with the door open anymore."