A man accused of slaughtering his girlfriend's cat was so obsessed with the tiny tabby that he wrote about it in his diary, the tearful woman testified yesterday at his bizarre feline-bludgeoning trial.

In the weeks before lay-about actor Joseph Petcka admittedly kicked cat Norman to death, he was already oddly fixated with earning the skittish orange and white cat's affection, Lisa Altobelli told a Manhattan jury.

The handsome screen hopeful would fill his diary with details of the "progress" he'd made toward actually petting aloof little Norman — as he crashed 12 hours at a time in her Greenwich Street apartment while she worked as a Sports Illustrated reporter.

Petcka loved his successful girlfriend, writing her love poems and tenderly drawing her portrait. But Altobelli saw the relationship as "casual," she told jurors, even as she lavished her love on Norman. She let the cat sleep at the foot of her bed, and called him "my little buddy," and "my little fluffball."

Norman, as well, wasn't feeling the love for the boyfriend.

"When Joe would come into the room, he would start hissing," Altobelli told jurors. "He was visibly terrified," she said of Norman. "He would run to the other side of the apartment."

Petcka claims he attacked the cat in self-defense. He faces a possible maximum of two years in prison.

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