So far, they have not come up with conclusive proof.

And yet there was no conclusive proof one way or the other.

So far they have yet to come up with conclusive proof.

At best, they say, there is no conclusive proof one way or another.

So far, however, there has been no conclusive proof for this, the most likely of the three scenarios.

I stopped for a second and tried to think what my conclusive proof was.

But conclusive proof of this phenomenon has not been established.

However, no conclusive proof has been found that this is V 452.

I'll have conclusive proof all too soon that they're dangerous!

However there was no conclusive proof to support this claim.