Sauber technical director Jorg Zander has left his position with immediate effect ahead of a reshuffle at the Swiss team.
Zander joined the team in late 2016 after working for Audi's now defunct World Endurance Championship project and oversaw the design of this year's C37. A replacement has not been named and the team said the current heads of departments would report directly to team principal Frederic Vasseur for the time being.
Zander has extensive experience in F1 having previously worked for Mercedes, Brawn, Honda, BAR, Williams and, during a separate spell at the team in 2006 and 2007, BMW Sauber.
The news comes just days after Sauber's best result in over two years with a sixth-place finish at the Azerbaijan Grand Prix. After a slow start in testing, this year's C37 has shown promise and with the help of an up-to-date Ferrari engine has closed the gap to the midfield compared to 2017.
Sauber currently lies ninth in the constructors' championship with 10 points from four races.