Personalities of the Buddhist Suttas
See: SN 4 87 The case of Vakkali is one of several cases of suicide we have in the suttas. Another, where the Bhikkhu is also declared to have achieved arahantship at the end is that of Godhika, S.i, 119; K.S.i,150; another is of the many bhikkhus that committed suicide after The Buddha instructed them to meditate on the foulness of the body. The fate of these latter is not declared, and since it originated in foolishness, it is doubtful it went well. The general rule is that one does not do to one's own body what one should not do to another's body, and therefore, suicide is, from the point of view of kamma, generally considered murder. In the case of those who have escaped "an evil end" after such a deed, they have done so by attaining arahantship. And, just for the record, we do have at least one case where a murderer - Angulimala (garland of thumbs - became arahant.
The two stories of Vakkali and Godhika are virtually identical. It is possible that the two stories got mixed up. I prefer to think that the two stories were, in reality, virtually identical. When I first began reading the Pali, I used to dismiss the stories of magic in the suttas and in the Jatakas. Now I have a much more flexible view. The "real" world is created by and limited only by the imagination. I have seen over and over again where a lack of belief in something has made someone blind to it's reality. I think what we see here is something that happens all the time, but which passes unnoticed for the most part. It is a variation on Downbound Confounded Rebounding Conjuration. According to this model, people do what they remember having done. Thus they are doing life over and over again, chasing the sensations of the past. They do the same thing year after year, month after month, day after day, and from moment to moment. What we don't usually think of with regard to this formula is that it also works on a macro basis: people doing what other people have done; populations doing what other populations have done, the world evolving and devolving over and over in approximately the same way each time. I am suggesting that what we are being given here, and in the several other places where stories of different people are told in identical terms (and especially in the Rebirth stories where the story in the previous birth is quite often identical to the story in the current life) is a hint at this phenomena.