Colin's Motorbike

Riddle: Colin recently bought a new motorbike. One morning, he polished the bike for his evening bike ride, closed the garage, and went to work. When Colin came back, he found that the motorbike was gone. The man called the police, and the officers questioned three neighbors. Jessica said that she had stayed home all day because she was sick. Elizabeth said that when she was walking her dog, she saw that the motorbike was still in the garage. Pete said that he had come to Colin's house to ask for some garden tools, but when nobody opened the door for him, he simply left. Who stole the motorbike?