Even if you saw someone do it, even if you captured it on video, until a judicial authority has rendered a decision, a suspect or defendant has not been proved guilty of the charges or allegations against him. Not only is it unethical (for a reporter, certainly, especially a reporter who did not witness the event) to describe this individual as, say, a "murderer" or "embezzler" or "shooter" without the qualification of words like "accused" and "alleged," but such descriptions could turn you into a defendant yourself, for libel.
In an action for libel (written) one does not have to prove damages. They are presumed. For slander, actual damages have to be proven, except in four situations:
The words charged the plaintiff committed a criminal offense;
The word impute or imply that the plaintiff has certain contagious diseases;
The words impute or attribute unchastity or adultery to any woman or girl;
The words are calculated to disparage the plaintiff in any office profession, trade, calling or business held or carried on him at the time of the publication.
Moreover, it doesn't matter what the truth ends up being, like in the case of an alleged crime, for example. If the person ends up being convicted of the crime later, but hadn't yet been convicted at the time of the libel or slander, you're still screwed if you failed to use "alleged" when talking about them.
There was a case not too long ago when a rookie British reporter, on her first assignment, actually, wrote the following:
“Two Asian women and five British ladies were arrested for prostitution by Dubai Police on Saturday.”
In one sentence the reporter disparaged two Asians by comparison, elevated five Brits to a level of unproven refinement, and convicted all seven of an alleged crime. The inconsistency of using a geographical region to describe the Asians and using a nationality to describe the Brits is bad enough, but all seven should have been "ladies" or "women", with no differentiation between them.
But the big one is, in reality all seven were either "arrested and charged" with prostitution, or they were "arrested for alleged" prostitution. They were all arrested, to be sure, but they were not arrested for committing the crime of prostitution, they were arrested for allegedly committing the crime.
A fine line, perhaps, but an important one if they're talking about you.