He was born on October 26, 1818 in Spain, the eldest son in a family of five children. At the age of 25, the young man took vows in the Dominican Order and just one year later, in 1844, was ordained a priest. His missionary journey took him from Manila to Macau, and finally he arrived in Đông Đàng Ngoài on September 12, 1845, taking the Vietnamese name An.

Father An was appointed to teach at the Nam Am Seminary in Hải Dương. There, he compiled the book "Latin Grammar" in Vietnamese to assist the seminarians. At just 31 years old, he was appointed by the Holy See as Coadjutor Bishop of the Trung Diocese (April 5, 1849).

In March 1850, Bishop An began a pastoral visitation in Hưng Yên. But the trip was soon interrupted by an intense crackdown and a severe bout of malaria, which left him bedridden in the Cao Xá parish for a time.

It wasn't until 1854, when the situation had calmed somewhat, that the Bishop organized a grand celebration in honor of Saint Dominic at Lục Thủy. The event gathered a large number of religious, priests, nuns, seminarians, and over 20,000 faithful. He also convened the Diocesan Council and organized a catechism competition among the parishes.

In 1855, the uprising of Lê Duy Cự and Cao Bá Quát broke out. Although this group tried to win over Catholics with promises not to persecute the faith, very few followed them because Bishop An had strictly forbidden the faithful from opposing the government. Thanks to this stance, local mandarins also became more lenient in enforcing the edicts banning Christianity.

In May 1858, someone denounced the Bishop to a High-ranking Mandarin who had come from the capital to Nam Định. He was arrested, put in chains, and held in solitary confinement for two months in Nam Định prison.

On July 20, 1857, during the reign of Emperor Tự Đức, Bishop José Diaz Sanjurjo was taken to the Bảy Mẫu execution grounds. In his final moments, he asked for a few minutes to pray: to give thanks to God for leading him to Đại Nam, to give thanks to his parents for giving him life and raising him, and to urge the faithful to always remain steadfast in their faith.

Bishop Sanjurjo - An was beatified on April 29, 1951, and was canonized by Pope John Paul II on June 19, 1988.