The reason I can't find you an example has more to do with not having access to a criminal law database. If I find an example, I'll post it.
I disagree with your analysis of the law but don't intend to bore everybodys' pants off by repeating myself or getting drawn into a tangential debate. There is enough in Julie's account to raise the distinct possibility that her involvement went much further than she disclosed and the relevance of that is mainly to account for her hesitancy in coming forward. What particular crimes she might have ended up getting charged with is not that important.
It is your legal theory that is flawed.
Fact pattern:
Bob witnesses Jill suddenly run up to Jack screaming at him that he is a cheating bastard, Jill shooting Jack dead and then driving away in a red Honda Civic.
A) Police arrive and Bob tells police he didn't get a good look at the shooter, how the shooter got away or what happened.
B) Police arrive and Bob tells police a black man tried to rob Jack but he refused to give up his wallet so the robber shot him dead then fled on foot
C) Police arrive and Bob tells police a white man shot Jack for some unknown reason then got into a blue Chevy and fled.
In scenario A is Bob guilty of any impeding justice charge on the basis of failing to disclose what he knows? No
Is Bob guilty in scenario B or C? Yes in both he is guilty because he provided false information with the intention of throwing police off the trail of the real killer.
In scenario A police are no worse off for having spoke to Bob than they were prior to speaking to him.
In scenario B and C though police are worse off because they were fed misinformation.
Your legal theory is that in scenario A Bob could also be found guilty because he lied saying he knew nothing when he actually did know something that would be useful to police and held that information back. But this legal theory has no support at all in case law which refuses to hold people liable simply for refusing to provide information they are aware of. In order to support a charge of impeding an investigation on the basis of a lie the lie must consist of disinformation intended to mislead not simply refusing to tell everything you know.
My fact pattern is not overly technical it is very simple so that even laymen can easily understand it.