MORE THAN a year after the coronavirus pandemic began, its origins are mysterious. The truth may take years to discover, but now is a good time to relaunch the search for it. A joint inquiry by the World Health Organization and China has run into trouble, as a group of 26 scientists pointed out this week in an open letter to the WHO. Both the possibility of a zoonotic spillover from animal hosts and that of a laboratory accident need independent, expert investigation — and it is time for a new team to seriously tackle the laboratory hypothesis.