The FBI has something called the Uniform Crime Reporting Program which publishes a report every year called Crime in the United States. Law enforcement agencies submit data about crime in their area, the FBI compiles it, and from this we know, for instance, that 16,692 persons were murdered last year and overall, 78.7% were male, 48.7% of the victims were white, 48.6% of the victims were black, and about the murderers themselves, where known, 89.9% were males, and 52.6% were black.

That is only the tiniest fraction of the information contained in these reports. They are an invaluable resource, and the FBI has been producing them since 1930.