Kajpr enrolled in the Jesuit novitiate in 1928 and was ordained in 1935. He served the parish of St. Ignatius Church in Prague beginning in 1937 and taught philosophy at the diocesan school of theology.
Between 1937 and 1941, he served as an editor of four magazines. His Catholic publications caught the attention of the Gestapo who repeatedly upbraided him for his articles until he was finally arrested in 1941.
Kajpr spent time in multiple Nazi concentration camps, moving from Terezín to Mauthausen and eventually to Dachau, where he remained until the camp was liberated in 1945.
On his return to Prague, Kajpr resumed teaching and publishing. In his periodicals, he spoke out against atheistic Marxism, for which he was arrested and charged with writing "seditious" articles by the communist authorities. He was found guilty of high treason in 1950 and sentenced to 12 years in the gulags.
According to his vice postulator, Kajpr's fellow inmates later testified that the priest dedicated his time in prison to a secret ministry, as well as educating prisoners about philosophy and literature.
Kajpr died in a prison hospital on Sept. 17, 1959, after suffering from two heart attacks. A witness said that at the moment he died he had been laughing at a joke.
The Superior General of the Jesuits gave his approval to open Kajpr's cause for beatification in 2017. The diocesan phase of the process officially began in September 2019 after Cardinal Duka obtained consent from the bishop of the archdiocese where Kajpr died in Slovakia.
"It was through the service of the Word that Kajpr irritated the followers of atheistic and agnostic humanism," Novotný said. "The Nazis and communists tried to eliminate him through long imprisonment. He died in prison as a result of this torture."
"His weakened heart broke when in the midst of persecution he laughed joyfully. He is a martyr who died laughing."