The detection of deception is a promising but challenging task. Previous exploratory research on deception in computer-mediated communication found that language cues were effective in differentiating deceivers from truth-tellers. However, whether and how these language cues change over time remains an open issue. In this paper, we investigate the effect of time on cues to deception in an empirical study. The preliminary results showed that some cues to deception change over time, while others do not. The explanation for the lack of change in the latter cases is provided. In addition, we show that the number and type of cues to deception vary from time to time. We also suggest what could be the best time to investigate cues to deception in a continuous email communication.