Mercedes team principal Toto Wolf described Aldo Costa as 'one of the pillars' of the Mercedes team
Aldo Costa, a key figure at Mercedes through their domination of the past few Formula 1 seasons, is to leave the team at the end of the month.
He joined as engineering director in 2011 and was in that role through their world title wins from 2014-18.
The Italian stepped into an advisory role for this season and is to join Italian race-car constructor Dallara as chief technical officer in January.
It is the latest step in a regeneration of Mercedes' technical department.
Costa had previously spent many years at Ferrari, where he was influential in their dominant era with Michael Schumacher in the early years of this century.
The Italian joined Ferrari in 1995 as assistant to chief designer Rory Byrne. He stepped into Byrne's role when the South African retired in 2004 and became technical director when Ross Brawn left Maranello at the end of 2006.
Costa eventually left Ferrari in mid-2011 after their car was not competitive enough to mount a title challenge against Red Bull that season.
Among many other projects throughout motorsport, Dallara builds the Haas Formula 1 car.
Mercedes F1 boss Toto Wolff said: "Aldo has been one of the pillars of our team since he joined in 2011 and he now leaves us with the same dignity and professionalism that have characterised his years with us.
"Aldo's passion for racing burns brightly - both in the engineering office and, sometimes, in the cockpit as well. He wanted to return to Italy to spend more time with his family and still has much energy and expertise to contribute to the motorsport community."
Aldo Costa spent 16 years at Ferrari before leaving to join Mercedes in 2011
Costa said: "After many years working at the pinnacle of our sport, I am excited to be able to contribute some of what I have learned to other racing series and to high-performance automotive projects outside racing.
"I remember writing to Giampaolo [Dallara] at the very beginning of my career for a job - at the time, there was nothing available, but he was able to open some doors for me in the industry.
"Now, many years later, it feels like the wheel has come full circle and I am proud to be joining this iconic company of Italian motorsport.
"One of my personal passions is to mentor and grow young talent, and it will be a focus for me to help attract and develop the next generations of Italian engineering talent at Dallara in the years ahead.
"It has been an extraordinary privilege to be part of Mercedes' development and success - and we have been able to build an incredibly strong group to tackle the challenges of the future."
