As a teenager in Rafah, Marzook was introduced to Sheikh Ahmed Yassin, a member of the secret leadership of the Egyptian Muslim Brotherhood.

Marzook travelled extensively throughout the Middle East during his years in Abu Dhabi, cultivating political and financial connections in support of his goal to establish an independent Islamist state in Palestine.

Abu Marzook was elected as the first head of the Hamas Political Bureau in 1992, overseeing its operations from Northern Virginia under the United Association for Studies and Research.

[4][7] Journalist Shlomi Eldar credits Abu Marzook's fundraising prowess, and his connections to donors in Europe and the US with saving the organization and developing its infrastructure in Gaza, including social service programs.

During meetings, Marzook reportedly explained Hamas's conditions for talks with Israel and pledged not to conduct operations against the United States.

[6] On August 1, 1993, Marzook reestablished the Hamas Political Bureau in Amman, returning to the United States three or four times per year to renew his green card and meet with U.S. officials.

[10] Officials from the Immigration and Naturalization Service arrested Marzook upon arrival at John F. Kennedy Airport in New York City on 27 July 1995 due to his presence on a terrorist watch list.

[9][12][13] In 2003, the Central Bank of Jordan froze the assets of Hamas leaders, including Marzook as a politburo member.

The assets of politburo chief Khaled Mashal, founder Ahmed Yassine, and senior officials Osama Hamdan and Imad al-Alami were also frozen.

"[17] In 2002, a federal grand jury in Dallas returned an indictment against Marzook for conspiring to violate U.S. laws that prohibit dealings in terrorist funds.

The indictment alleged that Marzook had conspired with the Richardson, Texas-based InfoCom Corporation and five of its employees to hide his financial transactions with the computer company.

Elbarasse was an assistant to Mousa Mohammed Abu Marzook, and was named an unindicted co-conspirator by a grand jury in Chicago after authorities searched the home and vehicle of Elbarasse and found bank records belonging to Marzook, deputy chief of Hamas's political wing.

[11][5] The Forward published responses to the interview from eight "prominent observers of the Middle East peace process", Laura Kam of The Israel Project, Israeli security analyst Yossi Alpher, Lara Friedman of Americans for Peace Now, Princeton University Professor Daoud Kuttab, Abraham Foxman of the Anti-Defamation League, Arab-American activist Hussein Ibish, David Keyes of Advancing Human Rights and political scientist Nathan Brown.

[24][25] When asked about the Re'im music festival massacre, Marzouk replied that it was a "coincidence", and that the attackers may have thought these were soldiers "resting".