The IPCC said there was "no case to answer" for misconduct against the man who led a triple murder investigation arising from the riots in Birmingham in August 2011. Detective Chief Inspector Anthony Tagg was in charge of the criminal investigation.
However, the police watchdog did say the family liaision officer, Detective Inspector Khalid Kiyani, who retired in October 2012, "would have had a case to answer for gross misconduct".
The watchdog said both officers' record-keeping was "deficient".
Haroon Jahan, Shazad Ali and Abdul Musavir were killed when they were hit by a car in Winson Green during the riots in Birmingham.
It emerged during the trial that defence barristers were never told of an offer made by police of immunity from prosecution for witnesses involved in the disorder until the 10th week of court proceedings.
The IPCC said the Crown Prosecution Service had since concluded there was "insufficient evidence to provide a realistic prospect of proving that either police officer had knowingly made a false statement and as a result committed the offence of perjury".
Eight men were acquitted of the murders in July 2012.