<p>Police lineups are conducted with varying delays between the crime and the lineup. Crime-to-lineup delays may adversely affect the detection of the presence and absence of the culprit in the lineup and may potentially affect guessing-based selection. In the present study we examined how these processes change across four crime-to-lineup delays. Participants viewed a staged-crime video and then completed simultaneous photo lineups after no delay or after a delay of one day, one week or one month. The results showed a significant decline in the probability of culprit-presence detection. The form of the decline is best described by a power function with the most rapid decline occurring at short crime-to-lineup delays. Eyewitnesses did not compensate the decline in culprit-presence detection by increasing guessing-based selection, as demonstrated by the fact that the probability of guessing-based selection remained constant across crime-to-lineup delays. The findings underscore the critical importance of conducting lineups as soon as possible after a crime to maximize the probability of memory-based-culprit detection.</p>