However, the case is not completely closed. Democratic Senator Mark Warner, the committee's chairman, said he was 'dismayed' there had been no hearing last year. While the closest known viruses to Covid-19 have been found in bats, the 'evolutionary distance' between them is thought to be 'several decades'. Because nobody has identified a virus thats 100% identical to SARS-CoV-2 in any animal, there is still room for researchers to ask about other possibilities.HOW LONG DOES IT TAKE TO CONFIRM THE ORIGIN OF A VIRUS? There are probabilities, and there are possibilities, said Banerjee.
the case is not completely closed because of chance.
( z0 cause :ARG0 ( z1 chance ) :ARG1 ( z2 close :ARG1 ( z3 case ) :ARG1-of ( z4 complete :polarity - ) ) )
(z0 / cause-01
    :ARG0 (z1 / chance-02)
    :ARG1 (z2 / close-01
              :ARG1 (z3 / case-03)
              :ARG1-of (z4 / complete-02
                           :polarity -)))
the case is not completely closed because of chance .
z4 :polarity 0
z2 :ARG1-of z4
z2 :ARG1 z3
z0 :ARG1 z2
z0 :ARG0 z1