FACTS are not "partisan".

[Atticus]

If you rob a bank and get caught, the footage from the bank's surveillance cameras clearly identifying you is no less accurate just because the cameras were installed by someone who belongs to another political party.

If some of the eyewitnesses actually know and detest you, that can be considered in assessing the truth of their testimony but, when corroborated by others plus the video, is certainly admissible testimony at your trial.

Republicans who whine about the "partisan" nature of Trump's impeachment are, in my view, in the same category as those who complain that showing video of them saying what they said is "unfair". Both are saying that facts aren't facts or, at least, that there are "alternative facts" that are "just as good".

[spooky3]

1. What if you admit the crime, but say it was a perfect robbery?

Those police are being mean because they don’t like you.