At a recent Pets Anonymous reunion, the attendees were discussing which pets they had recently owned. James used to have a dog. The person who used to own a mouse now owns a cat, but the person who used to have a cat does not have a mouse. Kevin has now or used to have a dog, I can't remember which. Becky has never owned a mouse. Only one person now owns the pet they previously had. Rebecca said very little throughout the meeting and nobody mentioned the hamster. Can you determine who owns which pet and what they used to own?