Catechist Peter Nguyễn Khắc Tự was born in 1808 in Ninh Bình. He dedicated himself to serving in the Apostolic Vicariate of Western Tonkin. At age 20, he returned to assist missionary Pierre Dumoulin Borie Cao, also known as Bishop Cao.

When Bishop Cao was arrested, Teacher Tự requested to accompany him, fully aware of the tortures awaiting them. In response to the bishop’s concerns, he expressed his steadfast loyalty and trust in God’s grace.

Teacher Tự was arrested together with the bishop in Bố Chính and then taken to Đồng Hới. At the tribunal, because he firmly refused to renounce his faith and declined to trample on the Holy Cross, he was flogged. Despite threats and attempts to bribe him, he resolutely replied, “Your Honor, I would rather die than deny my faith.” He endured brutal torture, was left exposed to the sun, and was even thrown into a pit of venomous snakes—but remained unharmed.

In prison, his greatest comfort was being jailed alongside Bishop Cao. The bishop’s example strengthened his faith. He also received confession and Holy Communion from Father Ngân.

On July 10, 1840, during the reign of Emperor Minh Mạng, catechist Peter Nguyễn Khắc Tự was beheaded at the Đồng Hới execution ground at the age of 32.

Catechist Peter Nguyễn Khắc Tự was beatified on May 27, 1900, and canonized on June 19, 1988.