In 1369 DR, he was involved in the kidnapping of Randal Morn himself under orders of the Zhent wizard Ilthond. In the end, the situation went bad for the Zhentarim and the Freedom Riders attacked the town, defeating the Zhent soldiers. Guthbert was likely killed in the fighting.
Guthbert was an amiable fellow, fearless in battle but was very slow in thinking. Thus he usually had with him a more capable second-in-command, such as the Cyricist cleric Asdag in Teshendale and the fighter Toren in Daggerdale.