There really isn't enough evidence to prove that he committed the crime, so it's (highly) 'improbable' that he'll be convicted.
The story includes a number of absurd 'improbabilities'. [=improbable events or situations]
The team made an 'improbable' comeback.
(..) B of A said they had a power outage, And Morgan-Stanley said their server crashed! Huh! That's weird! Meh, I will, I will call it, improbable Sue. Where do you have our position-mark? I think it's the same Mike What? Can you explain that to me please? (..)2015 The Big Short