VATICAN CITY - The Vatican is sending its former sex crimes prosecutor to Scotland last week to investigate "recent serious allegations of misconduct" surrounding disgraced Scottish Cardinal Keith O'Brien, who resigned last year after admitting to sexual misdeeds.

The Vatican and the Scottish church said Bishop Charles Scicluna will report on the situation.

O'Brien, once Britain's highest-ranking Catholic leader, resigned in disgrace as the archbishop of St. Andrews and Edinburgh in 2013 and recused himself from the conclave that elected Francis as pope in 2013 after unidentified priests alleged in British newspaper reports that he acted inappropriately toward them.

The men said they had complained to church authorities about O'Brien's conduct but that the church had failed to respond.

After initially denying the allegations, O'Brien eventually admitted that his sexual conduct had "fallen below the standards expected" of a priest, archbishop and cardinal. He apologized and promised to play no further role in the life of the Scottish church.

The Vatican ordered O'Brien to leave Scotland for a period of prayer and atonement, but until the National Catholic Reporter reported Scicluna's visit, the Vatican had never confirmed it was investigating the allegations.

The matter is particularly sensitive given O'Brien's rank as a cardinal. It's only the second known time that a cardinal has been investigated by the Holy See for sexual misconduct. The then-archbishop of Vienna, Cardinal Hans Groer, was forced to resign in 1995 over claims he molested youths in a monastery in the 1970s.