A PC would not have been sacked for his "extended" use of a Taser on a man who later died, the police watchdog said.
Jordon Begley, 23, died after Greater Manchester Police (GMP) officers Tasered and restrained him in 2013.
There was evidence PC Terence Donnelly used "excessive force", the Independent Office for Police Conduct (IOPC) said.
It concluded the officer, who has since left the force, would have faced misconduct proceedings but a dismissal would not have been "justified".
An original report by the organisation into Mr Begley's death, which found no individual officer had a case to answer, was quashed by the High Court in 2016 after it was found to be inconsistent with a subsequent inquest.
No 'immediate necessity'
A spokesman for the IOPC said a new investigation had uncovered "evidence of potential misconduct" which related to the PC's "decision to extend the use of a Taser longer than the automatic five seconds".
"We concluded that, had the officer still been serving, he would have had a case to answer... relating to an allegation he used excessive force, but not to the extent that his dismissal would be justified."
The officer said his reason for keeping his finger on the trigger was that Mr Begley had not "gone down as if he's gonna stay still and to listen to what we're going to say" and was "still kicking", the report stated.
He also could not see exactly what Mr Begley had in his hand, it said.
However, a tribunal found no "immediate necessity" for the extended discharge, as the Taser's barbs were in place, which meant PC Donnelly had the option of reactivating the device at "a moment's notice".
The report also stated that IOPC inspectors, who examined more than 3,000 pieces of evidence during the reinvestigation, found no evidence to substantiate a case to answer for misconduct for the four other officers investigated - PC Peter Fox, PC David Graham, PC Christopher Mills and PC Andrew Wright.
However, it stated that a fifth officer, PC Lee Moore, should face management action with regard to a statement he made at Mr Begley's inquest in regards to police conduct at the incident.
In June, Mr Begley's mother Dorothy said the investigation into his death was "a whitewash", adding: "Five years later, I'm still fighting for him."
IOPC deputy director general Ian Todd said it had been "a long and difficult journey for everyone involved in this tragic case, not least Mr Begley's family".
"I apologise to the family and the officers for any stress and anxiety caused by these necessary but protracted investigations."
A GMP spokeswoman said the force accepted the findings of the report and "continue to offer our condolences to Jordan's family".