FERGUSON, Mo. — One day after roiling tensions over the police shooting of a black teenager here began to subside, emotions flared anew on Friday as the police identified the officer involved but also released evidence that the victim was a suspect in a convenience store robbery moments before being shot.

The manner in which the police here released the information, which included a 19-page police report on the robbery but no new details about the shooting, led to the spectacle of dueling police news conferences, one led by a white officer who seemed ill at ease and defensive, and the other dominated by a charismatic black officer who expressed solidarity with the crowd even as he pleaded for peace.

The white officer, Thomas Jackson, the police chief in Ferguson, gave a series of incomplete accounts that sowed confusion about whether the officer who shot the teenager knew he was a suspect in the robbery. The black officer, Capt. Ronald S. Johnson of the Missouri State Highway Patrol, expressed his displeasure with how the information had been released.