Authorities say there have been several reports of unattended wallets being stolen during church services.
Investigators have not said exactly how many thefts have occurred.
The suspect is described as a white male in his early 20s with blond or brown spiked hair. He may be driving a dark brown or gray minivan.
Authorities cautioned people to keep their personal property with them and secure at all times and not leave items unattended.
If you have any information about these crimes, you're urged to contact Ventura County's sheriff's dispatch at (805) 654-9511.