Since his communications were monitored and censored by the Germans, Metropolitan Andrey used personal couriers to send messages to the Apostolic See of Rome, especially to Cardinal Eugène Tisserant and to Pope Pius XII.
When the horrors of the Nazi occupation were revealed to him, Sheptytsky tried to inform the Vatican. in March 1942, he drafted a letter to the Pope which was never sent. At the end of August, he wrote a longer letter to the pontiff. It is likely that the earlier draft was used to compose the August missive. He also wrote a cover letter to Cardinal Tisserant, and dispatched the two letters probably via Hieromonk Johannes Peters, a Studite monk of German extraction.
The March draft and the August letter to the Pope both mentioned the massacre of 130,000 Jews in Kyiv. This almost certainly refers to the Babyn Yar massacre. These letters reached the Vatican at the beginning of September 1942, and are among the first testimonies to the world about Babyn Yar.
From October 1941 to February 1944, Metropolitan Andrey Sheptytsky issued more than ten pastoral messages condemning violence and murder, especially as the result of ethnic or religious hatred. This included an excommunication of any member of his flock who committed murder and a vitandum (a form of shunning) by which other members of the Church were forbidden to associate with them. Due to German censorship, these messages were read from the pulpits of the churches. The most famous of these was issued in November 1942 and entitled "Thou shalt not kill." He is the only bishop in history ever to do this.
Below are English translations of the passages in Sheptytsky's letters that refer to Babyn Yar. The text of the second document and a photograph if its handwritten last was published in 1967 in the third volume of Actes et documents du Saint Siège rélatifs à la Seconde Guerre Mondiale (doc. 406).
Sheptytsky to Pius XII, draft, 28 March 1942
… As they advance eastward, the Germans are becoming increasingly aggressive and ruthless in exercising an entirely unbridled national selfishness. They regard all Jews as enemies of war and orchestrate massacres in which thousands of Jews perish along with their wives and children. For instance, in all the major cities of Ukraine, they exterminated every Jew who had not fled before their army— nearly 130,000 in Kiev, according to reports that appear to be authentic, and similar numbers in other cities.
Sheptytsky to Pius XII, 29–31 August 1942
… Today, the entire country agrees that the German regime is evil and almost diabolical perhaps to an even greater degree than the Bolshevik regime. For at least a year, there has not been a day when the most horrible crimes, murders, thefts and robberies, confiscations, and extortions are not committed. The Jews were the first victims. The number of Jews killed in our little country has certainly exceeded two hundred thousand. As the army advanced eastward, the number of victims grew. In Kiev, in a few days, they executed a hundred thirty thousand men, women, and children. All the small towns of Ukraine have witnessed similar massacres, and this has been going on for a year. At the beginning, the authorities were ashamed of such inhuman acts of injustice and attempted to ensure that there were documents which could prove that the local inhabitants or the militia were the perpetrators of these murders. Over time, they began killing Jews in the streets, in front of the entire population and without any shame.
Lest we forget.
May their memory be a blessing.
Вічна їм пам'ять.