Agnelli, the son of former Fiat CEO Umberto Agnelli and a member of the Italian car maker's board, spoke on Thursday at a club shareholders meeting in Turin.
"When there are problems I tend to look people in the eyes, ask them the questions directly and them judge them myself," Agnelli said. "I'm very calm, having spoken to him directly as soon as the case emerged, on his position. And his behaviour in the days and weeks that followed only confirm my initial feeling."
Kathryn Mayorga filed a civil lawsuit last month in Nevada claiming Ronaldo raped her in his Las Vegas hotel room in 2009. Police also reopened an investigation into the allegation at her request.
Ronaldo defended himself against the accusation at a news conference ahead of Juventus’ Champions League win against Manchester United. His attorney, Peter Christiansen, issued a statement on 10 October denying wrongdoing by his client.
Some of Ronaldo's corporate sponsors, including Nike and video game maker EA Sports, have expressed concern about the rape allegation.
"It's a personal case and the choices are up to him but I reminded him my door and Juve's door are always open to him and we're here to help and support him in any way," said Agnelli, who is also president of the European Club Association.
In July, Ronaldo left Real Madrid after nine years for Juventus, a move that cost the Italian club 112 million euros.
"He allows us to reach a wider audience and allows us to consolidate our position within the sports and entertainment industry," Juventus chief revenue officer Giorgio Ricci said.
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