Why Don't We Know Who Killed Michael Brown?

The police chief, Thomas Jackson, has repeatedly declined to identify the officer, who has been put on administrative leave.

In the five days since an unarmed young black man was fatally shot by a police officer here, the selective release of information about the shooting, and especially the anonymity granted to the officer, has stoked frustrations in this largely African-American community north of St. Louis, where residents describe increasingly tense relations with the police.

The police chief, Thomas Jackson, has repeatedly declined to identify the officer, who has been put on administrative leave. But on Wednesday, the chief did offer a new detail about the shooting, which has kindled nights of racial unrest and an unyielding police response with tear gas, rubber bullets and arrests.