I didn't do X but if I did he deserved it.

Breaking it down into two claims:

My tires were slashed

My neighbor has shown himself to be disreputable

Therefore, (I suspect) my neighbor slashed my tires.

It's a reasonable suspicion, sans deception, so, no, not a formal fallacy. Although, the case might be made for a non sequitur, or even an ad hominem (guilt by association).

It does seem more of a natural cognitive mechanism, or, what Dennett might suggest is a promiscuous teleological line of causal reasoning.

One's neighbor might be disreputable but does that mean s/he would act out violently? It would be natural to initially suspect it ( the usual suspects) but with no evidence to support it, it's just a reasonable theory of investigation and process of elimination. 

My keys are missing

My cat likes to play with my keys

Therefore, my cat took my keys. 

However unlikely, or even ludicrous, blaming someone or something else for one's misfortune is a common psychological projection. 

My neighbor is deplorable and a pariah in our neighborhood

His tires were slashed last night

Whoever did it, for whatever reason, he certainly deserved it.

Again, I don't see the fallacy, just more of a prejudicial judgment. 

This seems two faced. 

It isn't. 

Someone deserving X and actually getting X are two different things.

"She deserves that promotion" is a statement of opinion .

"She got/is getting/will get that promotion" is a statement of fact .

Even if the disreputable neighbour "implicates" himself by saying "if I did do it", this still doesn't imply that he did do it, since they proposed a hypothetical upon which they then gave their opinion .

No, there is no fallacy or contradiction here because it is a complex statement of the form: ¬p ∧ (p⇒q).
However, it is well known that the logical character of a material implication differs from the everyday use of "if" sentences. So I think the one who co-uttered this sentence actually wants to say: I didn't do it, but you certainly deserved it . This could be written as ¬p ∧ q.
As you can see, these two formulas are different, but in any case I can state the following:
1. This is not a logical fallacy, because there are no argument but only complex statement.
2. It is a matter of contingency, a complex statement which is sometimes true and sometimes false.