A Virtual Inhabitant is a kind of believable agent proposed in order to endow the attractive features of human-controlled characters to computer-controlled characters. In this paper, we specify the knowledge structure for Virtual Inhabitant to infer an alibi problem in virtual environment. An alibi problem is important problem which includes temporal-spatial aspect. Time and space don?t have pointed value but have ranged value in situation. We introduce three layer of abstraction to present time and space value. We expect that proposed knowledge structure can make Inference of Virtual Inhabitant more believable.