A source close to the matter confirmed to Investment Week that Tabbouche had left the firm to emigrate to Israel, where many of his family currently live.
The region is currently at the epicentre of a war with Palestinian group Hamas which has garnered global attention and criticism since the conflict began escalating on 7 October.
Tabbouche will take on an advisory capacity role until the new year to enable a "smooth transition" for the company, at which point he will officially depart from the firm, the source confirmed.
The company's joint CIO Nick Khuu will remain in the role by himself following Tabbouche's formal exit.
RIT Capital Partners records 'broadly flat' NAV total return in H1 2023
Khuu was promoted to the role back in March this year, having joined the firm in 2012.
The outgoing CIO has held the role for over a decade and the departure follows his decision to step down as director of the investment trust's fund manager J Rothschild Capital Management earlier this month.
According to persons close to the matter, Tabbouche's departure is not related to the recent performance of the trust, which has struggled in 2023.
The investment trust posted a slight drop in its net asset value total return for the first half of the year and it is currently running on a 25.36% discount, according to data from the Association of Investment Companies.
In the summer, Investec analysts issues its first ever ‘Sell' rating for a RIT on the portfolio, calling it "uninvestable" due to costs.
The management has sought to overcome the discount with a series of share buybacks throughout the year.