Now two teams of forensic linguists say their analysis of the Q texts show that Mr. Furber, one of the first online commentators to call attention to the earliest messages, actually played the lead role in writing them.

Sleuths hunting for the writer behind Q have increasingly overlooked Mr. Furber and focused their speculation on another QAnon booster: Ron Watkins, who operated a website where the Q messages began appearing in 2018 and is now running for Congress in Arizona. And the scientists say they found evidence to back up those suspicions as well. Mr. Watkins appears to have taken over from Mr. Furber at the beginning of 2018. Both deny writing as Q.

The studies provide the first empirical evidence of who invented the toxic QAnon myth, and the scientists who conducted the studies said they hoped that unmasking the creators might weaken its hold over QAnon followers. Some polls indicate that millions of people still believe that Q is a top military insider whose messages have revealed that former President Trump will save the world from a cabal of “deep state” Democratic pedophiles. QAnon has been linked to scores of violent incidents, many of the attackers who stormed the Capitol last year were adherents, and the F.B.I. has labeled the movement a potential terrorist threat.