It is absolutely clear the market had no connection with the origin of the outbreak virus, and, instead, only was involved in amplification of an outbreak that had started elsewhere in Wuhan almost a full month earlier,” he told CNN.

Ebright also isn’t ready to rule out the theory of the two Chinese researchers that the virus may have “leaked” from one of two labs near the Wuhan market, although one of the authors told The Wall Street Journal they withdrew the paper because it “was not supported by direct proofs.”

While Ebright said he did not believe the genome sequence of the virus shows any “signatures of human manipulation,” he said there is a risk that a lab worker could have accidentally been infected.

CNN was not able to independently verify the points made by Ebright, and the main author of the study — Botao Xiao — did not respond to CNN’s emails and phone calls requesting comment.