In the spring of 2010, Christopher Steele, a former British spy with a shock of graying hair and a quiet, understated manner, received some alarming news: Vladimir Putin, a lifelong ice hockey fan, had taken a sudden interest in soccer.
This was years before Mr. Steele compiled his now famous dossier on Donald Trump, with its references to clandestine meetings in Prague and, of course, “the pee tape.” In 2010, Mr. Steele, regarded among those who knew him as a serious and levelheaded MI6 officer, had only recently retired and opened his private intelligence firm in London.