Difference (if there is any) between 知るか and 知ったことか


From what I researched online, I have read that most of the times these
phrases are interpreted as "I don't care", "Who cares?" " "I don't give a
damn!" "It's none of my business!" etc (feel free to provide more examples,
these are just a few that I have seen)  

Most of the time I have seen 知るか, but the variant 知ったことか not so much, but it
was said in a video I watched recently. My questions would be, does this
phrase is most of the time interpreted with the above meanings?

Is there a difference in nuance when it's in the present/future tense 知るか and
past tense 知ったことか, and could the addition of こと work in the first variant?

Given the context where I heard 知ったことか I do not think the above meanings
worked well and I translated with the more direct meaning of the verb 知る=to
know, to be aware of, and given that it was in the past tense plus こと I
assumed it meant "a thing/matter that was known".

I'm gonna give the example where I heard 知ったことか . A bit of context, characters
A and B are fighting:

> A: 弟をまで利用して..そのザマか？  
>  B: 弟子など．．．俺の知ったことか !

The context is that B hurt a boy who was his little half-brother, but B did
not he had one, for he was elsewhere in the world and doing villain things. A
believed that B knew of his younger brother's existence and that's why he used
him in his plans, but B did not know about a brother, it was just the plot
y'know, had to bring these characters together...

Things happen, A and B fight and they say those things, B who was unaware of a
brother, to me it made sense if I could interpret his line "弟子など．．．俺の知ったことか !"
"Younger brother?" (with など I even thought of it like "the likes of",
"something such as" a brother) Is it something that I should know?!
(俺の知ったことか). If 知ったこと was said, wouldn't it be interpreted as "a matter which
is known, to me?", if I translated very directly? But I think "Something like
that....Is that something that should I know?"

I rephrased that line a bit to how I understand it like this:
（俺の知ったこと）＝前に俺が何かを記憶していた or another way, as a reply to A
"今の言ったこと、俺が知るべきだを期待しているか） I want to know if this sort of interpretation is
possible because I looked trough some comments on social media regarding this
and I mostly found things that mentioned the "I don't care" meaning, but that
doesn't quite make sense for B to say, "I don't give a damn about my brother",
if he didn't know he had one!

Hope I provided enough to offer me some suggestions about this, about the
differences, if there are any between the variants of those phrases and if
ultimately, they can be ambiguous, and 知るか isn't specifically just with that
meaning of "who cares", "don't give a damn" (どうでもいい）

Thank you in advance for any suggestions！




They are pretty much the same when they mean "none of my business" or "I won't
care whatever happens to it/you/etc", but 知るか also means "no way I know this".
For example when you saw a difficult quiz, 知るか is usually chosen. In addition,
I feel I see 知ったことか more often in fiction than in reality because it's
relatively long.

Looks like you're trying to analyze the "past tense" in 知った, but た in fixed
phrases often behaves idiosyncratically, and 知ったことかよ has little to do with
something in the past. It just means "I don't care" or "Should I care?" A
similar example would be ほら見ろ and ほら見たことか, both of which mean "Look, I knew
it", "I warned/told you (but you didn't listen)" regardless of the "tense" of
見る.

  * [Usage of plain i-adjectives or た form (悪かったｖ悪い、良かったｖいい etc）](https://japanese.stackexchange.com/q/21347/5010)
  * [Usage of doubled non-past tense "た"](https://japanese.stackexchange.com/q/5356/5010)
  * [Non conventional usage of the past tense](https://japanese.stackexchange.com/q/40733/5010)

