Christopher Aurier, 26, died at the hospital after being shot in the stomach outside a nightclub in Toulouse on Monday night.
The prosecutor's office confirms that a man has been arrested.
The local newspaper La Depeche writes that a quarrel about a girlfriend may have been behind the shooting.
Christopher Aurier was once seen as a greater talent than Serge, who is a year older, and both trained in Lens as young.
While Serge went on to play for PSG and the Ivory Coast national team before moving to Tottenham in 2017, Christopher never broke through at a higher level in football and played this season with the Toulouse Rodeo in the French Fifth League.