Sayers was facing charges relating to conspiracy to defraud the commonwealth in relation to income tax arising out of events that occurred almost 10 years ago.
The charges were not connected to Ausdrill but related to tax matters arising from arrangements put in place by professional advisers engaged by Sayers and a business associate at that time.
The Director of Public Prosecutions formally discontinued the charges Friday, bring the proceedings to an end after some procedural difficulties.
Earlier this month, a Supreme Court judge discharged a second jury after it was unable to reach a verdict on the case.
A jury also failed to reach a verdict in November last year.
“The Ausdrill board and management have remained fully supportive of Mr Sayers throughout the process and are delighted that the charge has been discontinued,” Ausdrill said.
The penalty for the dropped charges could have included up to 10 years of jail time.