"We feel like we put a lot of hard work into these issues and we feel they're not being taken in the spirit of which they are offered, and that is to improve the Atlanta Police Department," Beamud said.
Spokespersons from Mayor Kasim Reed's office did not respond to requests for comment. Following his 2009 election the new mayor voiced his support for the board and said his pick for police chief would ensure that Atlanta's 1,700 officers respect its authority.
Beamud acknowledged "things have improved" under new Police Chief George Turner, selected by Reed to replace Richard Pennington.
"Nonetheless there remain concerns," she said.
APD spokesman Carlos Campos said Beamud minimizes the changes made under Turner.
"This year alone, 16 Atlanta police officers have been dismissed as a result of Office of Professional Standards investigations, which is more dismissals than in the four previous years combined," Campos said, adding the APD resolved twice as many citizen complaints in 2010, compared with 2008.
Over that same period the department has also reduced the backlog of citizen complaint cases by 73 percent, the spokesman said.
"We know work remains in this area," Campos said. "A force with ethics, integrity and respect for citizens and their rights are the utmost importance."
Beamud's resignation takes effect at the end of this month. The former police officer said she plans to return to Boston to practice law.
"The struggles of the job have become pretty strong, and I think I'm ready to go home," she said Thursday.
--WSB Radio reporter Pete Combs contributed to this article.