Born and raised as a Baptist Christian, Rigg began studies at Yale university, and received his B.A. in 1996. He received a grant from the Henry Fellowship, to continue his studies in Cambridge University. That summer he went to Germany, and met Peter Millies, an elderly man who helped Rigg understand the German in a movie they were watching, 'Europe Europe', about Shlomo Pearl, a Jew who served in the Nazi army. Millies later told Rigg that he himself was a part-Jew, and introduced him to the subject which was to become his main research topic for many years

Back at Cambridge, Rigg offered the subject as his thesis, but was rejected on the grounds that it was "dead end science". Upon insisting, he finally received a year off, and small funding from Cambridge for a research trip back to Germany, under Professor Jonathan Steinberg. Steinberg contacted the media about the future research, which caused much debate about the scientific value of the outcome.. During this year, traveling under harsh conditions on bicycle throughout Germany, he gathered over four hundred recorded interviews, with "Mischling"s of this sort. He also discovered that he had Jewish origins. He followed up on the trip to Sweden, Turkey, Canada, and finally Israel.

He identifies himself today as Jewish, and studied in Israel at the "Ohr Sameach" Yeshiva. He also joined a short volunteer program at the Israeli army.

Rigg has done humanitarian activities in Romania, Bulgaria, the Bahamas, South Africa, and France.

His discoveries and writings have been used both by holocaust researchers, as well as holocaust denial and anti-Zionist groups, claiming that the Zionist regime is equivalent to or worse than the Nazi regime.

David Cesarani, professor for Jewish history in Southampton, England, and Raul Hilberg, emeritus of the University of Vermont judge Rigg’s work negatively, because they believe Rigg’s thesis is presented in a sensationalistic and unbalanced way.

Some scholars also resent that Rigg tried to gain public attention when his work was still in an early stage. Other scholars, like Richard J. Evans, history professor in Cambridge, and Omer Bartov, history professor at the Brown university, consider the titles of Rigg's books such as "Hitlers Jewish Soldiers" misleading, because the books are not about Jews but in most cases about "mixed Jews" as defined by the Nazi ideology, but not according to the Jewish view.