Why do you use the word "biased"? Maybe it is simply information that he didn't have before that can help him interpret the results of his own investigation? He isn't going to change his mind based on the police, but he could change his mind or modify his conclusions based on information that was relevant, that he did not have before, that came to him VIA the police.
I think that the ME is to do his own investigation, and give the cause of death based on physical observations and tests( toxicology,x-rays, etc). He then states wether or not the death was natural,accidental or a homocide.
By biased, I meant that it is not to be influenced.