this is bbc news. it is the scientific mystery of our times, with a hefty dose of politics mixed in. where did the covid—19 virus come from? talk of a laboratory leak was long dismissed as the stuff of conspiracies. now it�*s in play — only a theory, but certainly in play. joe biden says he�*ll release the results of a new investigation to the public. china says any suggestion it leaked from a lab is a "conspiracy" itself. the us senate is split over the formation of a capitol siege commission. democrats say a thorough investigation is needed. republicans argue there�*s nothing left to learn. also in the programme: the recent fighting between israel and hamas has revealed faultlines in america�*s relationship with its main regional ally.