The Independent Office for Police Conduct (IOPC) is looking into how West Midlands Police investigated the death of Harbans Lal, 61, who was hit by a motorcyclist in Darlaston a decade ago.
The force's methods in the case have previously been called into question after Mr Lal's killer was only charged in 2017, seven years on from his death, when it emerged motorcyclist Luke Guttridge was travelling faster than detectives previously thought.
Guttridge was given a suspended prison sentence last year but complaints from the victim's family have prompted the police watchdog to investigate whether the force's work was up to standard.
The IOPC said its investigation, called Operation Grey, would the force's actions following Mr Lal's death "including the initial fatal collision investigation".
The CPS decided not to prosecute Guttridge following the original investigation, but when it was later established he had been going faster than thought, he was charged with causing death by careless driving.
An IOPC document relating to the case, seen by the Express & Star, said West Midlands Police referred itself to the watchdog following last year's trial.
Mr Lal's daughter Jasvinder Devi, who first lodged a complaint in 2013, feels the investigation into her father's death was inadequate. In 2014, the force was ordered to reinvestigate a complaint she made alleging failings.
Ms Devi said the investigation was a "long time coming".
She said: "I am relieved but it has taken seven years for the police to allow the IOPC to investigate them."
Mr Lal, who worked for copper tube manufacturers Mueller Europe Ltd in Bilston for more than 30 years, was knocked down as he crossed Wolverhampton Street, Darlaston, in December 2010 while on the way home from the pub. His right leg was severed and he suffered other serious injuries.
An IOPC spokesman said: “We are independently investigating a complaint about how West Midlands Police investigated a collision in which Harbans Lal died at Darlaston, Walsall, in December 2010. The complaint centres around the forensic collision report and how matters in relation to that have been handled by the force since then.
“The original complaint in July 2013 about the conduct and standard of the collision investigation led to a review by West Midlands Police, which concluded that there was no case to answer. A subsequent appeal was upheld by the IOPC and we then directed WMP to re-investigate the complaint.
“Following conclusion of associated criminal proceedings and further communication between the complainant and the force, a voluntary referral was made to us by West Midlands Police earlier this year.
“We began our enquiries early in August after deciding an independent investigation was required.”