If the cops did indeed plant evidence then happy days for the defence since it should be easy to disprove. e.g. by simple handwriting analysis or other such means. But this is fantasy wishful thinking since he did write the words. So stick to the reality here. He shot the guy and confessed to it. Lord knows what else he said during interviews with the cops but probably lots. His defense team will attempt to disqualify evidence and diminish his culpability while transforming the trial into one about private health care. They only need one not guilty and that’s what they’ll do their best to achieve.