Mormon declines to tell us the background story of this servant. We learn that he had been in disguise in a location where he could hear of plans of the Kishkumen band, and that he was out at night. Past what Mormon tells us, there are other things we may learn. First is that he recognized Kishkumen. This indicates that his presence at a meeting where he could learn plans was sufficiently intimate to see faces and learn them. We must remember that there is no photography at this time, so recognition comes only through contact. Second, the fact that he was in disguise suggests an intent to lead a double life, which is the very definition of a spy. It is rather doubtful that that he was a spy on his own initiative, and it would appear that Helaman (or perhaps the previous chief judge whose brother was murdered) has instituted a plan of infiltration and spying.
We know that there was an organized movement on which to spy, but the fact that it was also apparently known in the height of government suggests that it was not as secret as Mormon made it appear. There were those who knew, and talked enough that the organization could be infiltrated, even if they had not ever given up Kishkumen as the murderer of Pacumeni I.
This spy has learned that there were plans afoot, and probably knew the day and time. Thus his being “out by night” was not an error, but a calculated attempt to thwart the plan.