The investigation was opened Tuesday following a letter from an adviser of the current bishop of Nice.
Dominique Laurens, the Marseille prosecutor, opened the preliminary investigation but specified that “no complaint” has yet been filed against the cardinal.
Ricard, 78, used to be the archbishop of Bordeaux, in southwestern France, until he retired from that position in 2019 to serve in his home diocese of Dignes-les-Bains, in the south of the country. In the 1980s, he was a priest in the archdiocese of Marseille.
In addition to any possible criminal investigation, Ricard could also be subject to church sanctions based on his confession.
The Vatican spokesman did not respond to requests for comment Tuesday about what would come of Ricard, including whether he would be removed from his Vatican duties. Among other things, Ricard is a member of the Dicastery for the Doctrine of the Faith, meaning he is a voting member of the Vatican office that adjudicates clergy sexual abuse cases.
There has been one known case to date in which a pope has defrocked a cardinal accused of abuse, the then-Cardinal Theodore McCarrick, an American who denied the misconduct allegations but was eventually found guilty by a church investigation of abusing adults as well as minors.
Earlier, Francis removed the rights and privileges of the late Scottish Cardinal Keith O’Brien after he was accused of misconduct with adults.