So... I think I have figured it out.
He didn't drink it.
First, the bleach bottle was almost empty on the day in question. There was less than 1/8 of a bottle left...if that.
Second, three year olds lie/pretend (sometimes its a fine line).
And third, there have been no symptoms that an acid was ingested into his body. (symptoms which would include blood in vomit and diahrea and burns on the tongue, throat, esophagus and stomach)
When I asked him again today about the incident...he repeated the same details. Except he added the "bad guy children" to the story. Apparently, he didn't die from the bleach drinking because the "bad guy children" took him down into the hole and fixed him (No, we haven't been letting him watch Lost...)
So, to summarize...
1. Drinking bleach is really bad.
2. Three year olds lie.
3. There was only a very tiny amount of bleach in our home at the time in question. (And it is kept on a high shelf.)
So, I think we are in the clear.
Now, onto the "pretend" vs "lies" review...