LONDON — Christopher Steele, the former British intelligence agent who prepared the dossier on Donald J. Trump’s supposed activities in Russia, has gone underground.

The strange story of the dossier, which United States intelligence agencies, the F.B.I., Senator John McCain and many journalists have had for weeks, if not months, and which Mr. Trump presumably must have known about, appears to have had personal consequences for Mr. Steele.

According to neighbors and news reports, Mr. Steele hurriedly left his home in Surrey, a county southwest of London, on Wednesday to avoid attention or possible retribution once his identity as the author of the dossier was revealed, first by The Wall Street Journal. The Journal reported that Mr. Steele had declined its interview requests because the subject was “too hot.”

Mr. Steele, 52, was a longstanding officer with MI6, the British equivalent of the C.I.A., serving in Paris and Moscow in the 1990s before retiring. In 2009, he started a private research firm, Orbis Business Intelligence Ltd., with Christopher Burrows, now 58. Mr. Burrows has refused to confirm or deny that Mr. Steele and Orbis wrote the memos that made up the dossier, initially under contract to a Washington firm paid to dig into harmful matters from Mr. Trump’s past.