What would the meaning of '之前知道' be? And '之前知道了'? If someone said '我之前知道【proposition】' would this imply that they knew it before, but no longer do? How about '我之前知道了【proposition】'?

What about when the time is specific such as ‘昨天我知道【proposition】’? Would this imply that I no longer know the proposition?

Thanks in advance.
There seems to be a cultural difference in usage here. ‘之前知道’ means you learned this before and still know it. 'I knew' often means 'I've forgotten', unless qualified like below.

A：That girl married that boy.
A:这个女孩和那个男孩结婚了。

B could answer:
B：I know.
B:我知道的。
    or
B：I already know/knew that.
B：我之前就知道了。 

A：Who did that girl marry?
A:她和谁结婚了？
B：I knew, but I can't remember now.
B:我知道是谁，但是我忘了。