Franciszek Gajowniczek, a Roman Catholic, was born in Strachomin near Mińsk Mazowiecki. After the reconstitution of sovereign Poland, he moved to Warsaw in 1921, married, and had two sons. He was a professional soldier who took part in the defense of Wieluń as well as Warsaw in September 1939. Gajowniczek was captured by the Gestapo in Zakopane and sentenced to forced labour in Tarnów. He arrived at Auschwitz on 8 October 1940. When a camp prisoner appeared to have escaped, deputy commandant Karl Fritzsch ordered that ten other prisoners die by starvation in reprisal. Gajowniczek (prisoner number 5659) was one of those selected at roll-call. When the Franciscan priest, Kolbe, heard Gajowniczek cry out in agony over the fate of his family, he offered himself instead (for which he was later canonized). Kolbe's exact words have been forgotten, but one eye-witness account records his words as: "I am a Catholic priest from Poland; I would like to take his place, because he has a wife and children." The switch was permitted and the punishment meted out. After all his cellmates died, Kolbe (prisoner number 16670) was put to death with an injection of carbolic acid.
Gajowniczek was sent from Auschwitz to Sachsenhausen concentration camp on 25 October 1944. He was liberated there by the Allies, after spending five years, five months, and nine days in concentration camps in total. He reunited with his wife, Helena, half-a-year later in Rawa Mazowiecka. Though she survived the war, his sons were killed in a Soviet bombardment of Nazi-occupied Poland in 1945 before his release.
After World War II
On 17 October 1971, Gajowniczek was a guest of Pope Paul VI in the Vatican when Maximilian Kolbe was beatified for his martyrdom. In 1972, Time magazine reported that over 150,000 people made a pilgrimage to Auschwitz to honor the anniversary of Maximilian's beatification. One of the first to speak was Gajowniczek, who declared "I want to express my thanks for the gift of life." His wife, Helena, died in 1977. Gajowniczek was in the Vatican once again, this time as a guest of Pope John Paul II, when Kolbe was canonized on 10 October 1982.
In 1994, Gajowniczek visited the St. Maximilian Kolbe Catholic Church of Houston, Texas, where he told his translator Chaplain Thaddeus Horbowy that "so long as he ... has breath in his lungs, he would consider it his duty to tell people about the heroic act of love by Maximilian Kolbe." Gajowniczek died in the city of Brzeg on 13 March 1995 at the age of 93. He was buried at a convent cemetery in Niepokalanów, 53 years after having his life saved by Kolbe. He was survived by his second wife, Janina.