Fiorentina ​and Cagliari have announced that they will be retiring the number 13 shirt following the tragic death of Davide Astori

Fiorentina captain Astori was found dead in his hotel room on Sunday morning ahead of their Serie A game away to Udinese, with the cause of death still unknown. 

The defender made over 170 appearances for Cagliari when he joined the side from ​Milan in 2008. He then signed for Fiorentina in 2015 on loan before the move was made permanent a year later. Astori, who was reportedly due to sign a new deal with La Viola on Monday, was set to make his 92nd appearance for the ​Serie A side at the weekend. 

statement released by Fiorentina read: “To honour his memory and make the memory of Davide Astori indelible, Cagliari and Fiorentina have decided to jointly withdraw the shirt with the number 13.”

Meanwhile, man​slaughter proceedings have since been launched by Italian prosecutors as they seek to determine the causes behind Astrori's sudden death. 

“We have opened criminal proceedings over the hypothesis of manslaughter," chief prosecutor Antonio De Nicolo told Radio Rai - as quoted by Football ​Italia

“For now, it’s been brought against unknown persons. We’ve arranged an autopsy, which will be performed soon. 

"For now, no-one is responsible, neither is there anyone who seems as if they could answer anything. The start of this judicial procedure allows us to identify any responsibility on the part of anyone."

Due to Italian law, the procedure is the only way the authorities are allowed to carry out an autopsy and, as such, there is currently no suggestion of foul play.