Marcin Budkowski, the head of the FIA's Formula 1 technical department, has quit his post with immediate effect.
The 40-year-old from Poland had been with the FIA for three years.
He was considered something of a rising star within the government body. Many had expected him to be an eventual successor to the likes of Charlie Whiting and Jo Bauer.
It's not currently known why he's decided to leave the FIA.
Due to the wealth of confidential information he had access to from his role overseeing Formula 1, he's been placed on three-month gardening leave.
Born in Warsaw, Budkowski grew up in Paris and London and was educated at École Polytechnique, the École Supérieure d'Aéronautique and Imperial College London. He specialised in aerodynamic engineering.
He first entered Formula 1 in 2001 working for Prost Grand Prix. The following year he moved to Ferrari as a computational fluid dynamics (CFD) aerodynamicist. He had risen to the position of aerodynamic project leader by the time he left Maranello in September 2007.
Budkowski subsequently moved to McLaren as senior aerodynamicist. Other roles he took during his time at Woking included team leader trackside aerodynamics, aerodynamic development project leader, and deputy chief aerodynamicist. He then became head of aerodynamics in November 2012.
Budkowski joined the FIA in October 2014, rising through a number of roles to become head of the technical department in February. In that capacity he has had access to advanced research and development concepts from across the Formula 1 teams.
Earlier this month, former Honda Formula 1 engine consultant Gilles Simon was announced as joining the FIA as Head of Technical. He was brought in with a specific remit to evaluate new technical solutions across the FIA's line-up.
Simon's appointment was part of a number of changes the FIA was making at the time to its technical division. A new department was created responsible for all the governing body's single-seater championships.
Charlie Whiting was appointed head of the department, tasked with developing comprising Formula 1, Formula 2, F3 and F4.
Budkowski had been placed in charge of the technical side, with Laurent Mekies responsible for sporting and championship management