June 26, and King Gustaf V of Sweden on June 30, subsequently pleaded with Horthy to use his influence to stop the deportations. Roosevelt specifically threatened military retaliation if the transports were not ceased. On July 7, Horthy at last ordered the transports halted. According to historian Péter Sipos, the Hungarian government had already known about the Jewish genocide since 1943. Horthy's son and daughter-in-law both received copies of the Vrba-Wetzler report in early May, before mass deportations began. The Vrba-Wetzler Report is believed to have been passed to Hungarian Zionist leader Rudolf Kastner no later than April 28, 1944; however, Kastner did not make it public. The first transports to Auschwitz began in early May 1944, and continued, even as Soviet troops approached. The Hungarian government was solely in charge of the Jews' transportation up to the northern border. The Hungarian commander of the Kassa (Košice) railroad station meticulously recorded the trains heading to Auschwitz with their place of departure and the number of people inside them. The first train went through Kassa on May 14. On a typical day, there were three or four trains, with between 3,000 and 4,000 people on each train, for a total of approximately 12,000 Jews delivered to the extermination facilities each day. There were 109 trains during these 33 days through June 16. (There were days when there were as many as six trains.) Between June 25 and 29, there were 10 trains, then an additional 18 trains on July 5–9. The 138th recorded train (with the 400,426th victim) heading to Auschwitz via Kassa was on July 20. Another 10 trains were sent to Auschwitz via other routes (24,000+ people) (the first two left Budapest and Topolya on April 29, and arrived at Auschwitz on May 2), while 7 trains with 20,787 people went to Strasshof between June 25 and 28 (2 each from Debrecen, Szeged, and Baja; 1 from Szolnok). The unique Kastner train left for Bergen-Belsen with 1,685 people on June 30. By July 9, 1944, 437,402 Jews had been deported, according to Reich plenipotentiary in Hungary Edmund Veesenmayer's official German reports. One hundred and forty-seven trains were sent to Auschwitz, where most of the deportees were murdered on arrival. Because the crematoria could not cope with the number of corpses, special pits were dug near them, where bodies were simply burned. It has been estimated that one third of