In a statement, the Pitt department called Mr. Liu an outstanding and prolific researcher and an excellent mentor.

"Bing was on the verge of making very significant findings toward understanding the cellular mechanisms that underlie SARS-CoV-2 infection and the cellular basis of the following complications," the statement read in part. "We will make an effort to complete what he started in an effort to pay homage to his scientific excellence.”

Ross police believe that Mr. Liu was shot by another man — identified later by the Allegheny County Medical Examiner’s Office as Hao Gu, 46, of Pittsburgh — who then got into his car parked about 100 yards away on Charlemagne Circle and killed himself.