John Ratliff, who resigned as president of Quintiles for “personal reasons” in 2013, is taking over as CEO of Covance Drug Development, which is now owned by LabCorp.

Burlington-based LabCorp named Ratliff to replace Deborah Keller, who is stepping down. Ratliff takes the job effective Oct. 1. Keller announced her resignation earlier this month.

Ratliff will also become part of LabCorp’s executive committee and report directly to LabCorp chair/CEO David King.

“John is a highly respected biopharmaceutical leader, with extensive experience in increasingly important roles in the industry,” said King in a statement. “Those who know him and have seen him in action as a leader are impressed by his strength as an executive. He has a stellar reputation in the CRO and pharma sectors. I am delighted that he has agreed to join us at such an exciting time.”

Ratliff was a long-time Quintiles executive, having been promoted from chief financial officer to chief operating officer in 2006 and later to president as well as COO in 2010.

He most recently was CEO of HUYA Bioscience International.

“LabCorp is a global leader in healthcare innovation, and the addition of Covance has strengthened its position as the world’s leading healthcare diagnostics company,” Ratliff said. “The Covance team has an unwavering commitment to quality and service, furthering the company’s strategy of bringing innovative new medicines to patients faster. I am excited to join a highly accomplished leadership team that is deeply committed to improving health and improving lives around the globe.”

LabCorp bought Covance last year in a deal worth more than $6 billion.