A lot of discussion on Forkner here, who certainly appears to have been negligent in performing some of his specific duties. But what about Michael Teal, the Chief Project Engineer? From a technical and certification standpoint, the buck stops with the CPE. He had the ultimate responsibility for the completeness and correctness of all certification deliverables submitted to the FAA. Here's his testimony before the Committee on transportation and Infrastructure:
https://transportation.house.gov/imo...20(9.9.20).pdf
It's 148 pages of testimony and covers a lot of ground, but I think the portion that starts at the bottom of page 70 is most interesting because it discusses in detail the internal business process by which MCAS was modified to extend into the lower speed regime, and how the FAA was informed of the change.
Many of the interesting parts of the testimony can be found by searching for the phase "I don't know".