The voice print for this section is quite different from the previous three chapters. The text now switches into third-party narrative accounts. It is difficult to determine whether the person writing the text is the same author in the previous chapters who is now simply using a different literary style, or whether a different author, or authors, are now writing the text.
We do not know who originally wrote these missionary stories. It could have been Ammon or maybe Aaron. Perhaps they combined and gave their homecoming report together when they returned home to Zarahemla and then filed their record. This text, however, is probably something that was written sometime later. It does not appear to be a contemporaneous record. It is retrospective, and the writer knew well how this was all going to turn out in the end as he began writing these narratives. He knew what was important to preserve in the record. There were undoubtedly many other things that happened to Ammon, Aaron, and the other missionaries that were not recorded.
In places where Ammon and Aaron were not the authors, possibly Alma the Younger fashioned the narratives in these reports. In Alma 17:2, it is recorded that Alma was thrilled to run into his four friends. He had not seen them for a very long time, and they rejoiced together. The record states that they swapped stories on what had happened since they were last together. After their reunion, Alma may have decided that their missionary experiences should be preserved. Under that scenario, Alma may have been the author of this section. Since Alma was chief judge for a period of time, it may even have been a court reporter continuing to work for Alma who recorded these missionary narratives. Because of his conflicts with Nehor and the Ammonihahites, Alma would have been particularly interested in tying in with the encounters of the sons of Mosiah with Amulon and the followers of Nehor in the land of Jerusalem. It also may be that Mormon wrote or reworked these accounts based on the records that were in his possession. Mormon would have been especially interested in the successes of these Nephites in converting Lamanite kings, which was something he himself would have yearned to do but never could accomplish.