A Cairo prosecutor ordered on Friday that a lower-ranking policeman be detained for four days pending investigations into a street shooting a day earlier in the working-class district of El-Darb El-Ahmar.
On Thursday, a brawl between the policeman and a taxi driver let to the policeman shooting dead the man; the interior ministry said the shooting was "accidental."
The policeman was arrested on Friday by police.
During the prosecution’s questioning, the policeman, known as Mostafa Veto, said he attempted to fire his gun to scare the victim but not to kill him.
The prosecutor’s decision followed hearing the testimonies of five eyewitnesses who were at the scene where the policeman murdered the driver.
The witnesses told the prosecutor that the argument between the driver and policeman started over the Taxi fare.
The policeman promised the driver LE200 (around $25) for the ride but only paid LE20 (around $2.55), witnesses said in their testimonies.
An interior ministry statement following the incident said the policeman fired his gun to disperse a crowd of locals who had gathered and were sympathising with the driver, leading to the death of the driver.
Cairo security directorate in an earlier statement said the policeman had shot dead the driver "by mistake."
Hundreds of people converged outside Cairo security directorate to protest the death late on Thursday.
The policeman ran away from the murder scene, in fear of the angry mobs. But police later located him in a hospital with some injuries sustained during his running away from the crowds.
The incident comes on the back of a public fury over alleged abuses by police in recent weeks.