The police aren't accepting it, and they are going forward with an investigation:
From the article:
Evanston police Cmdr. Tom Guenther said the coroner's finding of suicide would not affect how police conduct the investigation. Asked if the finding ruled out any possibility of foul play or an accident, Guenther said, "I don't think we're going to jump to any conclusions at this point."
I think it is prudent to examine the case thoroughly. People will have questions, and being able to give as full an account as possible will help people to understand what happened and how. Certainly, no public official would want to hear for years afterward that there was a cover-up or a shoddy investigation.
I'm not convinced that the police think the coroner is wrong simply because they are looking for a complete picture.