Gender neutral reflexive pronoun — equivalent to "himself" and "herself"

How would you refer to a gender neutral subject with a reflexive pronoun?

It is unbelievable how a perpetrator will cast oneself in the role of victim.

That does not seem right. Is there a better word other than "oneself"? I thought "oneself" would refer to the narrator. Here I try to refer to the subject.

Themselves: It is possible to use a 'singular they' for pronouns, but to say "themselves" surely can not be correct as a gender neutral reflexive pronoun? According to this article, it would only seem to make sense when qualified by a singular they.

Themself: "The form is not widely accepted in standard English" according to the Oxford dictionary.

It is unbelievable how they, as a perpetrator, will cast themselves in the role of victim.

I'd like to avoid making the sentence this complex.

This is just another version of the he/she, him/her dilemma: English lacks singular pronouns that include both genders. I like @drm65's approach to avoiding the problem. The other likely option is to specify both:

"himself or herself"

It is unbelievable how a perpetrator will cast himself or herself in the role of victim.

Or:

"him or herself"

It is unbelievable how a perpetrator will cast him or herself in the role of victim.

Update:

Another approach is to just choose a verb that isn't reflexive:

It is unbelievable how a perpetrator will play the role of victim.

That's not always possible or best, e.g. when you're trying to emphasize exactly that reflexive aspect of the issue. But play is obviously shorter and simpler than cast him or herself in the role of, so it's worth considering unless there's a good reason to use the wordier version.

Update 2:

This question and my original answer are nearly 9 years old now, and there have been some significant changes with respect to personal pronouns in the interim. There's a greater awareness now of gender neutral and non-binary pronouns. In some contexts, a phrase like him or herself that's meant to be inclusive (compared to just himself) might be insensitive. Themself seems to be gaining acceptance even if it's not yet widely used. As the obvious singular form of the commonly used themselves, themself seems like a good choice for being inclusive while still being fairly conventional.

There are a number of other gender neutral third person reflexive pronouns such as hirself, zirself, xyrself, and coself. If you're talking about a specific person and know which pronouns they favor, use them.

Perhaps by 2029 there will be a more clear-cut answer.

You could circumvent the problem and avoid overcomplexity by merely pluralizing the subject:

It is unbelievable how perpetrators will cast themselves in the role of victim.

This is what I would do in this case, as neither oneself, themselves, or themself are widely endorsed here, and as there is no such thing in English as a singular gender neutral reflexive pronoun.