A YOUNG mum told yesterday how she is too frightened to go in her garden - after she was attacked by a "killer" Siberian chipmunk. Roxanne Whelan spotted two of the snappy critters when she popped out of her house for a ciggie. One ran towards her and hopped on a sofa she keeps in the garden, a couple of feet away from her. Roxanne, 20, said: "It was staring right at me and wasn't frightened of me at all. The next thing I knew it was jumping straight towards me and went on the attack. "I thought it was...