FERGUSON, Mo. - Two years after Michael Brown's shooting death put a national spotlight on Ferguson police, the suburban St. Louis city is struggling to maintain the number of officers it needs.

The department is facing 13 vacancies. It's down to a staff of 36 compared with 55 in 2014. Some officers have retired, while others who spent months dealing with protests and heavy scrutiny left for different jobs.

Mayor James Knowles III says finding qualified applicants has been tough and that diversity continues to be a goal. The force in the Missouri city was mostly white at the time of Brown's fatal police shooting.

Law enforcement experts say Ferguson isn't alone and that a number of police departments are struggling to fill their ranks.