Updated at 7 pm with comments from Dotson, Mayor Francis Slay, and the police union.

A 18-year veteran of the St. Louis Police Department who has spent the last 18 months assigned to City Hall as the operations director for Mayor Francis Slay is the chief of police for the city.

The Board of Police Commissioners on Friday evening announced that Capt. Sam Dotson would replace chief Dan Isom, who is leaving in January to take a position with the University of Missouri-St. Louis.

"It is humbling to realize that in the departments's 200-year history, there have only been 33 others appointed to this position as chief," Dotson said. "I'm replacing a very good chief. As a result of his leadership, the department is and will continue to be a great department."

Dotson says he was at City Hall at the unveiling of the mayor's holiday card when he got the call that the police board wanted to talk to him.

Credit (Julie Linder/St. Louis Public Schools) Sam Dotson with the winner of the mayor's holiday card contest shortly before the police board informed him he had been chosen as the next chief.

"It's kind of like getting called to the principal's office," he said, agreeing that yes, it turned out well for him.

Dotson will lead the department as it transitions from state to local control. He says the close relationship he developed with Mayor Francis Slay during his 18 months as operations chief will only help with that process.

"I can talk to him, I understand where his priorities are, and I think he understands me as an individual," Dotson said.

He added that he make it "my job, my mission, my goal" to keep political influence out of the department as the transition occurs. He also pledged to be open and transparent with the public about the department and how it operates.

In his remarks, Slay called Dotson an "excellent choice."

"He demonstrated his ability time and again to take on tough tasks and get them accomplished," the mayor said. "He was someone who was able to work with all components of city government, and certainly as we go through local control, he'll be able to hit the ground running to make this a smooth and seamless transition."

In a statement, Jeff Roorda, the business manager of the St. Louis Police Officer's Association echoed Slay's sentiments. Dotson, Roorda said, often helped mediate between the Association and the Slay administration on collective bargaining issues.

"We didn’t always get our way but we always got a sympathetic ear and an earnest effort to help on matters within his control," Roorda said. "I don’t have any anticipation that our relationship with Chief Dotson will be any different than our relationship with Captain Dotson."

The president of the union, David Bonenberger, said he hoped Dotson would help officers and their commanders work together to "come up with strategies and the implementation of strategies that will succeed" at reducing crime.

Isom had degrees in criminal justice. Dotson got a management degree from Webster University and an MBA from Fontbonne - a a course of study he calls a conscious choice.

The department, he says, is very good at its crime-fighting mission.

"But we’re also a $173 million enterprise, and that’s human resources, that’s benefits, that’s fleet management, that’s a variety of things that happen in any corporation," he said. "I think having 18 years of real, practical police experience and then an education in management is going to help."

Dotson says he’ll continue with Chief Isom’s "hotspot" policing initiative, which put additional officers in high-crime areas. He also says he’ll be looking into adding technology where appropriate, including cameras and data-crunching tools.

And, he added, he just got Isom's cell phone number - and plans to call it often.

Before heading to City Hall, Dotson was the chief of staff to the Board of Police Commissioners. He also spent time in the intelligence division, and was captain of the 7th Precinct when a disgruntled employee opened fire at the ABB factory at Union Ave. and Natural Bridge Rd.

Follow Rachel Lippmann on Twitter: @rlippmann