Prosecutors at the San Francisco District Attorney’s Office are being accused of withholding evidence in hopes of convicting a San Francisco police officer of excessive force. The NBC Bay Area's Investigative Unit has learned a criminal investigator for the DA’s office, Magen Hayashi, testified Thursday that she was ordered by her own co-workers – attorneys inside the district attorney’s office – to withhold evidence, and said she believed she would have been fired if she refused. District Attorney Chesa Boudin and his office did not respond to requests for comment. The allegations stem from the ongoing criminal case against San...