あまりにも ＋ しまったのでした

[HelplessNexus]

So, the sentence I'm having trouble deciphering is this excerpt from the story, ”走る名人”.
The sentence is:
”なんと「走る名人」はあまりにも足がはやすぎておいかけていたどろぼうをおいぬいてしまたのでした。”
I know what あまり would normally mean, but I've seen it around being used with にも, but I haven't really paid much attention to it until just recently. What is the closest translation you could get with that?
As far as しまたのでした goes, it's kind of the same issue with that, I just haven't paid very much attention to it, although I have less of an idea of what this means than I would with あまりにも.

If anyone could help me with this, I would appreciate it wholeheartedly.

[SomeCallMeChris]

”なんと「走る名人」はあまりにも足がはやすぎておいかけていたどろぼうをおいぬいてしまたのでした。”

And what do you know, the Master of Running had such a surplus of excessive speed that when he caught up with the thief, he kept going right past.

In this case, あまり is taking on its meaning of 'excessive', which is doubling-up the meaning of 'はやすぎて'. You could take あまりにも out, and the sentence would mean the same basic thing, it would just be less emphatic about it.
あまりにも is, I think, just a case of に making it into an adverbial form so it can modify 'はやすぎて', and も is doing one of its normal jobs, pointing out that something is a remarkable amount.

～しまたのでした should be ～しまったのでした
～しまった - expresses regret or 'oopsness' (if that were a word) of the preceding verb.
の makes it explanatory
でした just puts a polite-past cap on the sentence.

[HelplessNexus]

Lol, I realized I misspelled しまった in basically the entire post coming back to this thread.
I'll go back over a few things and get these down, thanks for the help, I appreciate it