BALTIMORE — The acquittal Monday of a police officer charged in the arrest of Freddie Gray, the black man who suffered a fatal spinal cord injury while in police custody last year, immediately renewed questions of whether any of the six police officers charged in the case would be convicted in connection with his death.

Officer Edward M. Nero’s acquittal on four charges for his role in the opening moments of Mr. Gray’s arrest was a second blow to the prosecution’s sweeping case, announced as Baltimore was still seething after the unrest following Mr. Gray’s death in April 2015. The first trial, against Officer William G. Porter, ended in a hung jury in December, touching off legal maneuvers that brought proceedings against the officers to a temporary halt.

But legal experts said Judge Barry G. Williams’s finding was a narrow one that does not forestall the possibility of convictions against other officers charged in the case. They said Judge Williams’s ruling turned not on a wholesale rejection of prosecutors’ broad legal theory, but rather on his determination that Officer Nero, 30, was a bit player in Mr. Gray’s arrest.

Judge Williams, who ruled on the case after the officer opted to forgo a jury trial, said in his verdict that there were other officers who played — or who could have reasonably been expected to play — a bigger role in the encounter. And while that is no guarantee that other officers will be found guilty, it is those officers who will stand trial in the coming months.