The acting commander, Willis, wrote in the memo that prosecutors have requested that detectives bring witnesses to them after they conduct interviews. That prosecutor is then assigned to the case to see it through to trial, a change from the past when supervisors reviewed evidence. He concluded that that additional legwork has too often been derailed by "scheduling conflicts."

Willis declined to comment for this article.

Police in Maryland are not required to get approval from prosecutors before filing charges. But for a decade, under an informal agreement, police have refrained from charging murder cases until prosecutors review the evidence first.

Jessamy had long pushed for explicit rules that would prevent police from charging various types of serious cases unless they received approval from prosecutors, but police and city officials pushed back and the effort failed.

Both police and prosecutors stressed that they have a better working relationship than ever and are constantly in communication to make improvements. Cheshire, the Bernstein spokesman, said the prosecutor's goal is to "build stronger cases for prosecution."

That was often the refrain from Jessamy, who was characterized as an obstructionist by a string of police commissioners and then-Mayor Martin O'Malley.

When Bernstein criticized her for not taking cases with only one witness — an issue that formed the basis of one of his television advertisements — Jessamy said she never had a policy of outright rejecting such cases. But, she said, "it doesn't do anybody any good to take cases to trial without sufficient evidence, because then they can never be tried again."

"When a prosecutor says 'We need this and this and this,' it's trying to get the best cases to get the best results. I think it's constructive tension," Jessamy said at a candidate forum.

Bernstein went on to defeat Jessamy, ending her 15-year tenure at the helm of the city state's attorney's office.

He is working to implement a number of changes, including a community prosecution model that assigns prosecutors to geographic areas.

His office has dropped at least one murder case brought by city police. In January, detectives charged 31-year-old Hassan Muhammed with first-degree murder in the killing of Cherrie Gammon near Leakin Park. Charging documents cited "witnesses" who said Muhammed was one of three men who took Gammon from her home and shot her in the head. The witnesses said Gammon had been working as an informant.

Six weeks later, prosecutors dropped the case before bringing it to an indictment, saying the investigation was "continuing." No additional charges have been brought in the case.

Baltimore Sun reporter Tricia Bishop contributed to this article.