When someone is suspected of criminal activity, one of the most important questions they are asked is if they have a credible alibi. Playing back past events in our minds, however, is not like playing back a video recording. Recollections of locations, dates, and companions can become muddled with the passage of time. If a suspect’s memories are out of line with documented events, a once-plausible alibi can crumble and may be seen as evidence of guilt.