Theranos yesterday made further changes to board of directors, as the ailing biotech start-up faces civil and criminal investigation into whether it defrauded investors. The company also announced the retirement of Sunny Balwani as president and chief operating officer.

The latest additions to Theranos’ board include Fabrizio Bonanni, retired in 2013 from his position as executive vice president at independent biotechnology company Amgen. In his 14 years with Amgen, Bonanni, served in numerous roles, including as senior vice president, quality and compliance and corporate compliance officer; senior vice president, manufacturing; and executive vice president, operations, overseeing the company’s global production and supply chain activities, as well as quality, process development, drug delivery devices, engineering, and environment, health and safety.

While the company expands its executive team, Bonanni “will work in a special capacity with management as it builds on its operations and quality systems infrastructure,” Theranos said.

The other additions to the board will have a “direct role in decision-making and shaping the company,” Theranos said. These members include William Foege, epidemiologist and former director of the U.S. Centers for Disease Control and Prevention, and Richard Kovacevich, former chief executive officer of Wells Fargo.

Foege has been working closely with the company and the scientific and medical advisory board as Theranos prepares to publicly introduce its technologies. Both Foege and Kovacevich previously served on Theranos’ board of directors before joining its board of counselors, an advisory group. Foege also serves on the company’s scientific and medical advisory board.

Theranos said it’s also implementing a new organizational structure with dedicated corporate divisions for technology and clinical operations. The company has been undertaking searches for multiple executive positions, and Balwani “will continue to support the transition process through its completion,” Theranos said.

The appointment of Bonanni and the other board members comes a month after Theranos expanded its scientific and medical advisory board, whose members advise the company on the integration of its technologies into routine clinical practice, the upcoming publication and presentation of its work in scientific journals and at scientific meetings, and other clinical initiatives.