Diagnostic Products Corp., a Los Angeles-based manufacturer of medical testing equipment, promoted Sidney Aroesty, the company’s senior vice president of operations and chief operating officer, to the additional post of president.

Chief Executive Michael Ziering, who held the additional title of president, will remain as CEO.

Aroesty, 58, had been performing many of the duties as president already, said company spokesman James Brill. “It’s just to broaden senior management. It formally provides him with the title,” Brill said.

Diagnostic Products, which manufactures equipment that can detect minute quantities of chemicals in human tissues and fluids, remains under government scrutiny on a variety of matters.

The company has been banned by the Food and Drug Administration from submitting new test applications while the agency investigates its clinical testing procedures.

The company is completing a corrective action plan and has said it hopes to resolve its issues with the FDA by the end of the first quarter.

The company is also under criminal investigation by the U.S. Attorney’s Office in Los Angeles over insider trades conducted by officers, directors and employees while the FDA review was underway. Aroesty is among the officers who traded stock during that period.

In addition, the company is in settlement discussions with Department of Justice and Security and Exchange Commission after disclosing managers at its Chinese subsidiary engaged in kickbacks.

The personnel move follows the election of John J. Reith to its board of directors earlier this month.

Reith has served as president of a forensic accounting firm and is the second outside director to be added to the company’s board in the last two years as part of a plan to more professionalize management of the company.

The company now has eight directors, and the board has authorized the addition of another. Brill said there are no immediate plans to do so.