In this case we are dealing solely with people's memories, which makes it very difficult. Along with the fact that the police often aren't allowed to give their opinions on these matters, and it's sensationalist nature playing off prejudice against the police for higher ratings.
In the case of statistics news, you can sometimes glean out the exact numbers of the study and where they came from. In science, the exact result of the experiment. In politics, the whole speech/statement and as much of it's context as you can reasonably acquire. It often involves circumventing the news to do this though.