Saint José Diaz Sanjurjo was born on October 26, 1818 in Spain. He was the eldest of 5 siblings in the family. In 1843, he joined the Dominican Order and took vows. A year later, in 1844, he was ordained a priest.
Along with other young monks, Father Sanjurjo set off as a missionary to Manila, then Macau and finally arrived in Tonkin (Vietnam) on September 12, 1845. In Vietnam, with the Vietnamese name An, he was appointed to teach at the Nam Am Seminary in Hai Duong. Here, he compiled the "Latin Grammar" book in Vietnamese for seminarians. On April 5, 1849, at the age of 31, he was appointed Coadjutor Bishop of the Diocese of Tonkin by the Holy See.
In March 1850, Bishop An went on a pastoral visit to the parishes in Hung Yen region, but this visit was cut short due to intense pursuit by the authorities. The bishop also suffered from a severe malarial fever, so he had to return to Cao Xa parish and was bedridden for some time.
By 1854, when the situation was relatively calm, Bishop An organized a grand celebration of the Feast of St. Dominic in Luc Thuy. Many priests, nuns, seminarians and over 20,000 faithful from all over attended. He also convened the Diocesan Council and organized a catechetical contest among the parishes.
In 1855, when Le Duy Cu and Cao Ba Quat rebelled against the court, the Bishop prohibited the faithful from joining the rebellion, even though the rebels promised not to persecute the religion. Thanks to this, the local authorities relaxed enforcement of the king's ban on Catholicism. However, in May 1858, Bishop An was arrested after being accused of being the head of the Western religion. He was imprisoned for two months in Nam Dinh.
On July 20, 1857, under King Tu Duc's reign, the Bishop was sentenced to death at the Bay Mau court. Before execution, he prayed and thanked God for guiding him to preach in Dai Nam (Vietnam). He also thanked his parents for giving birth and raising him, while urging the faithful to remain steadfast in their faith.
Bishop Sanjurjo-An was beatified on April 29, 1951 and canonized on June 19, 1988.