After a two-week non-jury trial, Judge Howard Shore ruled that the girl, now 14, intentionally set a fire in her backyard last May 13 then set another blaze the next day in her neighbor's backyard that sent an ember nearly a half-mile to spark the Cocos fire.
The girl was convicted of three arson counts and one misdemeanor count of allowing a fire to get out of control.
Shore ruled that the teen acted willfully and maliciously in setting the fires, but said there was no evidence to suggest she intended to harm anyone or burn homes.
“Clearly, she was aware of the risk,'' the judge said. "She knew for years it was wrong.''
The girl, then 13, told investigators she knew that intentionally setting a fire was wrong but she wanted to see what would happen if she did.
She knew she was doing something wrong, and she did it anyway,'' Deputy District Attorney Shawnalyse Ochoa said in her closing argument.
Ochoa said the girl expressed glee and laughed when she told her sister about the May 13 fire.
The next day, the girl went to her room after setting the second fire, allowing that blaze to grow into a larger fire which sparked the Cocos blaze, the prosecutor said.
Ochoa said there was no evidence to suggest that someone else started the Cocos fire in a nearby canyon, as the defense claimed.
In her opening statement, Ochoa told the judge that girl went into her backyard with a lighter last May 13 and set a branch on fire. The teenager then went back in the house and told her sister, ``There's a fire out back,'' according to the prosecutor.
Firefighters responded and extinguished the small blaze, but the next day, the girl posted a photo of a fire burning in Carlsbad on social media, then went out to her neighbor's backyard, where she set another fire, this one spreading to nearby trees, Ochoa said.
Two Cal Fire investigators determined that an ember from the fire behind the girl's home traveled .44 of a mile to spark the Cocos fire, according to the prosecutor.
The girl will be back in Juvenile Court April 15, where rehabilitation, not punishment, is the goal, Ochoa said.
The Cocos fire was one of more than a dozen brush fires that erupted in hot, dry and windy conditions last spring. Officials set the cost of extinguishing the fires at nearly $28 million.