Kevin Nunes was shot dead in September 2002 but five men jailed for his murder were freed on appeal.
Police and crime commissioner (PCC) Matthew Ellis said Mrs Sawyers had "no case to answer on misconduct or gross misconduct" relating to the case.
Ms Sawyers welcomed the decision.
Police believe Mr Nunes was a drug dealer who was shot in an execution-style killing in Pattingham after straying into another gang's territory.
But the men jailed for his murder were freed after it emerged concerns over the credibility of witnesses were not disclosed to the defence.
This prompted an investigation into the police's handling of a key witness and how disclosure was dealt with afterwards.
In January 2014, the Independent Police Complaints Commission (IPCC) said it would be submitting files to the Crown Prosecution Service (CPS) over the case for prosecuting senior officers, including Mrs Sawyers, for either attempting to pervert the course of justice or criminal misconduct.
However, the CPS said there was not enough evidence to proceed.
Publishing his response, Mr Ellis said while it was clear "something went wrong in relation to the investigation of the murder", Mrs Sawyers was not guilty of misconduct.
"My conclusion is that, whilst there were undoubtedly different actions and decisions that should have been taken at the time, the IPCC report does not produce evidence Mrs Sawyers has a case to answer in respect of misconduct or gross misconduct," he said.
"I have been clear, however, Jane Sawyers could have been more intrusive and sceptical about the actions of others at the time."
Mrs Sawyers said: "I welcome the determination the police and crime commissioner has reached."
The IPCC said it was waiting for all of the forces involved, including West Midlands Police, to respond to its report.
The temporary chief constable of Staffordshire Police, Jane Sawyers, will not face misconduct charges over the fatal shooting of an alleged drug dealer, the force's commissioner has said.