The most important aspect of this that I think most people are missing is that they are specifically trying to bias the public into thinking he definitely did it. There is no "allegedly" in how they've treated him, they are actually using the positive public sentiment about what he did to continue to build the idea that it was definitely him and we don't need to go to court to prove it. The public loving Mangione and believing he definitely did it is actually in many ways beneficial to their case. It helps solidify the idea in the general public eye that "he did it" before any court case has looked at the facts.