DALLAS (CBSDFW.COM) – With Dallas Police Chief Renee Hall’s resignation after only three years on the job, it may seem like the position has become a revolving door.

But experts say Dallas is no different than other big cities.

Dallas Police Chief Renee Hall will have had the shortest tenure of any of her predecessors over the last three decades when she resigns at the end of the year.

Dallas Police Chief Renee Hall (CBS 11)

It’s part of a trend experts say other major cities are also experiencing.

“For most big city police departments the tenure of a police chief is only about 3 to 4 years,” says Doctor Alex Piquero, a criminologist who worked at UTD for nine years and now teaches at the University of Miami.

He says Chief Hall faced uphill battles from a shortage of officers to the Botham Jean shooting as well as criticism over her handling of downtown protests.

“She came into the department and the city in a very bad situation a lot of crime a lot of stuff going on,” says Piquero.

Renee Hall’s predecessor, David Brown, retired after seven years and was the city’s longest serving chief since the 1960s.

David Kunkle held the job for six years before that and Terrell Bolton for four.

Piquero says don’t expect future chiefs to be around as long as those.

“It’s turnover, it’s different job opportunities it’s a variety of different things,” says Piquero.

Over the past 20 years, every time the city brings in an outsider to run the department they are followed by someone promoted from within.

The department’s two largest police associations both want someone chosen from inside to be the next chief.

The Dallas Police Association tells CBS 11 News that “going outside would be disastrous.”

The National Latino Law Enforcement Organization agrees and says there’s “no time for a learning curve.”

Finding a new chief that both officers and community leaders agree on won’t be easy according to Piquero.

“On a football field all 11 players aren’t best friends but they all have a job to do they all have one goal,” says Piquero.