For many years, deception detection using polygraph tests has been used in criminal investigations. In particular, a technique known as guilty knowledge test (GKT) or concealed information test (CIT) has been shown to be effective in both laboratory and field settings. This test is designed to determine whether a suspect possesses crime-specific knowledge that only the perpetrator of a crime, not uninvolved people, would be expected to have. However, the central mechanism underlying this technique continues to remain unclear, because the traditional peripheral autonomic measures-such as electrodermal, heart rate, and respiratory activities-do not have sufficient response specificity. Recently, event-related brain potentials (ERPs) have been expected to fill the gap between peripheral and central processes. This paper provides a brief research review of deception detection using the P300 wave of the ERP. A larger amplitude of the P300 for the critical item that only the perpetrator is aware of is taken as an index of crime-specific knowledge. Although some researchers interpreted this P300 enhancement in terms of deception-related or memory processes, available evidence suggests that stimulus meaning in a broad sense is the most critical variable for this response. Possible directions for further research are proposed.