Apple has lost a key member of its platform architecture team. According to a new report from CNET, Gerard Williams III has departed Apple after nine years at the company. Williams served as a senior director in platform architecture.

Williams is said to have led development of numerous A-series processors, starting with the 64-bit A7 chip and ending with the A12X. The A7 processor was first used in the iPhone 5S in 2013, while the A12X is found in the current generation iPad Pro lineup. Prior to joining Apple in 2010, Williams worked at ARM for 12 years.

Over recent years, CNET says Williams’ role has evolved to include overseeing the layout of Apple’s processors:

Williams isn’t the only platform architecture to have departed Apple over recent years, though. In 2017, Google poached Manu Gulati from Apple. Gulati had served as a senior chip architect for Apple, with Williams taking over his role in 2017.

It’s standard for chip designers to pack more and more features — like the CPU brains of the device, GPU graphics and memory — onto the same physical package to improve battery life and reduce the size of the chips.

Earlier this year, rumors circulated that Apple’s SVP of Hardware Technologies Johnny Srouji was on the shortlist of candidates for the then-vacant Intel CEO position. Ultimately, however, that did not come to fruition, with Intel instead naming Robert Swan its new CEO.

The departure of Williams is notable for Apple, who is putting an ever-increasing focus on its custom silicon. Williams is named on more than 60 patents for Apple, and it’s likely that his work will be seen in future Apple processors that have yet to be publicly released.