District police on Friday revamped their entire mobile crime lab division, telling more than 80 officers responsible for collecting, marking and analyzing evidence that they are being transferred to patrol.

The move is a step toward replacing sworn law enforcement officers with civilians ahead of the scheduled Oct. 1 opening of the new $220 million Consolidated Forensic Laboratory that will be run independently of police and prosecutors.

Authorities announced the shakeup in an internal police teletype obtained by The Washington Post. About 20 officers will be transferred Sunday, the memo said. An additional 60 will continue to work in the lab temporarily, a move a deputy mayor said would ensure adequate staffing and allow the officers to train their successors.

As word of the transfers spread, some officers and prosecutors privately raised concerns over the loss of experienced technicians who handle the most sensitive of cases, including burglaries, rapes and murder.

Kristopher Baumann, the head of the police union, called the move an affront and said that it reneges on assurances from the city that the crime lab officers were safe in their jobs during the transition to the new facility.

“We invested an enormous amount of resources to train these officer technicians,” Baumann said. “These are our experts in evidence, and the idea that we’re going to summarily move them out of their positions without vetting or setting up replacements would not be a good idea.”

Gwendolyn Crump, chief spokeswoman for the D.C. police, declined to comment.

Deputy D.C. Mayor Paul A. Quander Jr. said hiring civilians with college degrees is cheaper and more efficient than using sworn officers in evidence collection.

“We’re removing officers from their desks and other ancillary types of jobs,” Quander said Friday night, “and we’re putting their badges on the street.”

In a letter to Baumann, Quander said the “transition will be gradual to ensure that newly hired civilian technicians are properly certified and trained.” Many other departments across the region use civilians in some capacity to gather and analyze evidence, in what has become a technical, scientific field.

The District’s new state-of-the-art crime lab at E Street SW, between the Federal Center and L’Enfant Plaza Metro stops in Southwest will put disparate forensic divisions in a central location and will expand the department’s ability to run tests and scrutinize evidence.

City Council members authorized the lab and removed administrative authority from police and prosecutors, in part to try and avoid problems involving faulty and contaminated test results that have beset other labs across the country. The civilian director answers to the mayor.

But officers in the District’s forensics division said their experience is invaluable, and they think their training and time as a sworn officer helps them understand investigations and guard against the dangers of working in high-crime areas.

Some prosecutors in the U.S. attorney’s office say they worry about losing officers who are seasoned in testifying at trials, translating complex science to jurors and withstanding cross-examination.

“This could hurt us and make it more difficult to persuade jurors concerning the quality and professionalism of the organization,” said a prosecutor, who spoke on the condition of anonymity because he is not authorized to speak publicly.