That is not correct.
In WI law, the presumption is that the defendant was in fear for their life, and was justified to use deadly force.
The prosecution must prove that they were not in order to convict.
Now, weather the jury follows the law is another question.
If you want to follow the testimony in this trial go here: https://legalinsurrection.com/
The fellow reporting is well know for understanding/practicing the law of self-defense. Enjoy