The blur between the Clinton’s personal and public interests is hard to penetrate.

But an examination by The Times suggests that Mr. Blumenthal’s involvement was more wide-ranging and more complicated than previously known, embodying the blurry lines between business, politics and philanthropy that have enriched and vexed the Clintons and their inner circle for years.

While advising Mrs. Clinton on Libya, Mr. Blumenthal, who had been barred from a State Department job by aides to President Obama, was also employed by her family’s philanthropy, the Clinton Foundation, to help with research, “message guidance” and the planning of commemorative events, according to foundation officials. During the same period, he also worked on and off as a paid consultant to Media Matters and American Bridge, organizations that helped lay the groundwork for Mrs. Clinton’s 2016 campaign.