In chapter 20 the reader finds out something about a plan which the current Receiver and Jonas have considered. Both want to change the Sameness and so they decided that Jonas should escape from the community and should find and go to Elsewhere. For the community his disappearance would look like an accident. Jonas and "The Giver" want to stage that Jonas fell into the river and was drowned. He wouln't be able to return to the community but all the memories which he had already received would return to the citizens. The current Receiver will stay there and will help the citizens to handle the new situation with feelings and chaos. Jonas will be away forever and the Receiver will be with his daughter when his work is finished. His daughter, named Rosemary, is the female who was assigned as "Receiver of Memory" but she decided to be released. It tells something about the failed selection before Jonas was selected for this job.
This is a possibility for a "Wanted" or "Missed" poster. I think the community could try to find Jonas in this way.