Three weeks before the inauguration, Mr. Broidy emailed invitations to coveted inaugural events to Angolan officials. He also sent them a version of a proposal under which Angola would pay Circinus as much as $64 million for security services over five years. The Angolans submitted a $6 million payment to Circinus three days before the inauguration, correspondence shows, though the company did not collect any additional funds from Angola, according to people close to Mr. Broidy.

One of the Angolan officials invited by Mr. Broidy, André de Oliveira João Sango, who was then serving as the director of external intelligence, was identified by The Times’s TV show, “The Weekly,” on the red carpet at a candlelight dinner attended by Mr. Trump the night before the inauguration. Another of the Angolan invitees, João Lourenço, has since been elected the country’s president.

At an informal inauguration week dinner at the Trump International Hotel near the White House, Mr. Broidy introduced Mr. Trump to two politicians from Romania, from which Circinus was seeking contracts valued at more than $200 million. One of the Romanian politicians, Liviu Dragnea, was facing corruption charges that have since led to a three-and-a-half-year prison sentence.

Mr. Dragnea, Mr. Lourenço and Mr. Sango were among the individuals named in a subpoena sent to Mr. Trump’s inaugural committee in April.

The Embassies of Romania and Angola in Washington did not respond to requests for comment. But Romanian news outlets have reported that the Justice Department has asked Romanian authorities for assistance in collecting information from Mr. Dragnea and others about their inauguration week visit to Washington.

Also named in the subpoena was Denis Sassou-Nguesso, the longtime president of the Republic of Congo, who has been accused of funding a lavish lifestyle with public resources. He was invited by Mr. Broidy to a handful of inauguration week events, including the candlelight dinner, while Circinus was pursuing business in that country. The business never materialized, and Mr. Sassou-Nguesso declined the invitation to the inauguration festivities, according to people close to Mr. Broidy.

The inaugural committee has responded to the subpoena, a person familiar with the committee said. The subpoena to the committee was first reported by The Wall Street Journal and was issued by the United States attorney’s office in Brooklyn.