They told the three judges that Diack and his son, Papa Massata Diack, were at the heart of a scheme that solicited bribes worth millions of euros from Russian athletes to cover up failed doping tests and allow them to continue competing.
“It was corruption at all levels,” public prosecutor Arnaud de Laguiche said in closing remarks.
The prosecutors also said Diack obtained $1.5 million of Russian funds while negotiating sponsorship and television rights to help finance Macky Sall’s campaign for the 2012 Senegal presidential election, in exchange for slowing anti-doping procedures.
The maximum sentence the prosecution could have sought was 10 years.
In his testimony, Diack, 87, said he had not sought to protect the athletes, some of whom later participated in the London 2012 Olympics, but to ensure the cases did not come to public attention at once and cause a scandal.
The finances of World Athletics, then called the International Association of Athletics Federations (IAAF), were at the time in bad shape and slowing the doping cases helped save a sponsorship deal with Russian bank VTB, Diack said.
The prosecutor said Diack became used to “living like an emperor”.
The prosecution sought a five-year prison sentence for Papa Massata Diack, who fled France for his native Senegal after the French investigation began and was tried in absentia.
A lawyer for World Athletics told the court the body sought 41.2 million euros in damages: “They destroyed athletics’ honour. The big-time sponsors have gone. We had to jettison the IAAF brand.”
Reporting by Tangi Salaun; Writing by Richard Lough; Editing by Kevin Liffey and Chizu Nomiyama