To be dan l’kaf zchus, I guess they felt that it is the same thing l’maaseh. Sometimes when you give too many details about something, people miss the point. L’maaseh, he was being held hostage. Presumably the murder was self-defense (or defense of others) so l’maaseh, it’s really the same, but if you tell people he’s being held for murder, people will start getting suspicious.
Also, he might not want people to know about it.