Tonya Mallory, the president and chief executive officer of Richmond, Va.-based Health Diagnostic Laboratory (HDL), resigned Sept. 23. Although HDL was the subject of a recent Wall Street Journal article and is under investigation by the federal government, the company says that Mallory’s resignation is unrelated and is for personal family reasons. Joseph McConnell, M.D., co-founder of the company and its chief laboratory officer, will take over as president and CEO. Mallory will continue to serve as a company board member and an adviser to McConnell. Mallory said she is leaving HDL to help her brother run a new business. In a letter to employees posted on the company’s Web site, Mallory wrote, “Many of you know that my brother lost his wife a little over two years ago. He has recently started a new business close to home to avoid what was a two-hour round trip commute each day. The new venture will permit him to keep his young kids in their supportive community. I am leaving HDL, Inc. to help him get his new company off the ground in an effort that we hope will give his family financial security in addition to allowing him more time with…