This kind of instance is different than what the OP was talking about. Tampering with evidence and obstruction of justice would be soemthing like changing the scene of the crime ON PURPoSE.
For example, FR should have been charged with that by the defense for changing around things in the room with the broken window. Of course she did not do it on purpose, but they could have tried to have a case to have her charged. But her moving things around in an alleged burglary scene wouldn't make her a partner in crime.
Same for AK if she'd covered the body and locked the door.
Now, if you are committing a crime, like robbery with others and one of your partners shoots someone in the commission of the robbery, then yes, you will be charged with murder in the US even though you did not pull the trigger or order your partner to do so.
IMO the court would never charge someone for running into their room to check to see if anything was stolen or damaged. Especially if the police were right there too.
Her 'moving things around' doesn't factor into a burglary of one's OWN STUFF.
This was what I think jjenny was saying. If AK let RG in or was in any way involved in what happened... she is just as guilty as the one (if not her) that struck the fatal blows.