Despite it happening on 1 April, between 06:00 and 07:00, investigating officers say the nude run between Petit Bot and Icart is no laughing matter.
Anyone who saw or can identify the runner is asked to contact PC 62 Flatres by calling 725111 or by emailing Jordan.flatres@guernsey.pnn.police.uk.
Alternatively, people can contact CrimeStoppers anonymously on 0800 555 111.