summit in 1982 under the auspices of President of Germany Karl Carstens. In 2010 Ratzinger indicated he would be prepared to testify to aid investigations into claims of abuse at the Regensburger Domspatzen choir in Germany. The Regensburg Diocese said that a former singer came forward with allegations of sexual abuse in the early 1960s, predating Ratzinger's tenure from 1964 to 1994. Allegations of sexual and physical abuse under his directorship A man who lived in the choir-linked boarding school until 1967 contended that "a sophisticated system of sadistic punishments in connection with sexual lust" had been installed there. Der Spiegel quoted the man, the composer Franz Wittenbrink, as saying it would be inexplicable that the pope's brother did not know anything about it. Ratzinger admitted slapping pupils in the face. He commented: "At the start, I also slapped people in the face, but I always had a bad conscience". He said he had been relieved when corporal punishment was forbidden in 1980. Ratzinger denied any knowledge of sexual abuse. A Vatican spokesperson stated that the allegations on sexual abuse, particularly the Regensburg case, are a campaign aimed against the pope and the Roman Catholic Church comparable to Nazi propaganda. A lawyer commissioned by the choir to look into the accusations concluded that over 200 young singers were abused to various degrees, with at least 40 of the cases involving sexual violence, and that he must assume that Ratzinger had known. A report in 2017 faulted Ratzinger "in particular for 'looking away' or for failing to intervene" and also stated that, "with a high degree of plausibility", between the years 1945 and 1992, 547 boys were victims of physical or sexual abuse, or both. Later life Ratzinger retired from his position as director of the choir in 1994 and was made canon in Regensburg on 25 January 2009. In 2005, during a visit to his brother in Rome, symptoms of heart failure and arrhythmia led to a brief admission at the Agostino Gemelli University Polyclinic. On 29 June 2011, Ratzinger celebrated 60 years as a priest and gave an interview on the topic, during which he noted that during the ordination ceremony, "My brother was the second to youngest, though there were some who were older." He also noted that "I have the stole and the cassock from that day". He celebrated his 90th birthday in 2014 with Benedict XVI