Complex sentence: While David Rigler was giving his deposition he discovered that Jean Butler Ruch had goaded Genie's mother into suing, which according to him was when the scientists first realized the extent to which Ruch affected Genie's mother's perception of them.
Split into simpler sentences: While David Rigler was giving his deposition, he discovered that Jean Butler Ruch had goaded Genie's mother into suing. According to him, this was when the scientists first realized the extent to which Ruch affected Genie's mother's perception of them.