It is not clear how often the Justice Department investigates police killings of blacks compared with whites. A justice official said the department did not track civil rights inquiries or subsequent prosecutions related to the conduct of law enforcement officials or prison guards based on the race of the victims. That is because the two statutes that provide for such inquiries, which led to criminal charges in 47 cases against 70 defendants in the most recent fiscal year, do not require race to be a factor.

Regarding the level of attention given to Mr. Hammond’s death, a search of the Nexis news database showed that in the three weeks after he was killed, including the night of his death, there were 145 mentions of “Zachary Hammond” and “police” or “Zach Hammond” and “police” in United States newspapers and wire services. By comparison, there were 704 mentions of “Samuel DuBose” and “police” or “Sam DuBose” and “police” in the similar period after his death, and 1,593 mentions of “Walter L. Scott” and “police” or “Walter Scott” and “police” in the similar initial period.

Image An undated photo of Zachary Hammond provided by Eric Bland, the Hammond family's legal counsel.

The lack of publicly disclosed video of Mr. Hammond’s death helps explain much of why it has not drawn more notice, said Richard Cohen, president of the Southern Poverty Law Center, a longtime civil-rights organization based in Montgomery, Ala.

Yet he added: “The reality is that this killing maybe doesn’t get quite as much attention because it doesn’t fit into the current narrative that’s sweeping the country.”

Mr. Cohen said Mr. Hammond’s death “reflects that police violence is not confined to one race of victims.”

Still, black Americans suffer disproportionate police violence. “And there is no doubt that police violence has racial dimensions, because communities of color are so much more heavily patrolled than white communities,” and because many officers — and many people generally — believe there is a greater presumption of danger with African-Americans, Mr. Cohen said.