The son of René Emile Belloq was, like his father and uncle Claude, an archaeologist. When his father disappeared mysteriously on an island near Crete in 1936 with only Indiana Jones and Marion Ravenwood returning unharmed, the son took it upon himself to track Jones in hopes of discovering the truth of what happened there for himself. Over time he came to believe there was a score to settle between himself and his father's old rival, feeling Jones' account at what happened regarding the Ark of the Covenant to be disrespectful.
From at least 1938 to 1957, the man kept records on Jones' activities through second hand information. In 1957, he planted the notion that Jones was involved in Communist activity to the police force in Jones' home town of Bedford, threatening the professor's job at Marshall College.
After he found out Jones and Ravenwood were due to wed, Belloq's son decided to give the pair respite for their honeymoon before taking revenge.