Bishop Peter Le Tan Loi of Can Tho confirmed on Dec. 19 that the Holy See authorized the beatification ceremony at the Tac Say Pilgrimage Center in southern Ca Mau province, where Diep's remains are enshrined.
Loi said Cardinal Luis Antonio Tagle, pro-prefect of the Vatican's Dicastery for Evangelization, will preside at the beatification as Pope Leo XIV's special envoy.
"This is a special gift from God," Loi said, describing the decision as a call for Catholics to follow Diep's "faithful witness, deep love for God and self-sacrificing service to others."
Diep is set to become the first 20th-century Vietnamese martyr officially on the path to sainthood — a landmark moment for the local church, where memories of war, colonialism and ideological conflict continue to shape religious life and church-state relations.
Born in 1897 to a farming family in An Giang province, Diep was ordained in 1924 and spent most of his priesthood serving poor people in the Mekong Delta. Assigned to Tac Say Parish in 1930, he became known for his tireless pastoral work and his willingness to defend vulnerable people during the turmoil of the First Indochina War.
On March 12, 1946, Diep was killed at Tac Say. For nearly eight decades, the circumstances of his death were clouded by rumor, with many Catholics believing he had been murdered by communist forces — an assumption reinforced by Vietnam's long history of conflict and persecution.
A Can Tho Diocese investigation has now officially rejected that narrative.
The 63-page investigation, conducted between 2011 and 2017 and released publicly in November, concluded that Diep was killed by two Japanese deserters seeking revenge after Japan's defeat in World War II. The findings were reviewed and approved by the Holy See.
Loi said Vatican regulations require documents related to investigations of martyrdom, heroic virtue and longstanding veneration remain confidential for 50 years after an investigation concludes, which is why witnesses' names were abbreviated in the published report.
According to sworn testimony from 23 witnesses — including 13 with firsthand knowledge — the two Japanese soldiers beheaded Diep from behind.
Mr. D., a layman, testified that Mr. B., his friend, said the soldiers seized Diep and took him to a dry pond next to a neighboring house. They ordered him to kneel, then drew their swords and struck him from behind. "The two men who killed Diep were Japanese soldiers," he said. "One was named N., and the other was named Th."
Mr. S., a member of a Buddhist family who owned the land where the killing took place, testified that the motive was resentment toward Western powers.
"Why did those two Japanese soldiers kill Diep?" he said. "They hated the West because Japan had been defeated by the West. They saw Diep as following the Western religion and siding with the West. Because they hated the West, they killed him to take revenge."
The investigation also documents tensions between Diep and local landlords, whom he confronted while defending poor farmers and displaced families — including victims of the 1944-45 famine that killed up to 2 million people in northern Vietnam.
Ms. N. testified that she had heard public reports of a land dispute between Diep and Mr. Z., a wealthy landowner. "My father said Diep possessed valid land documents while Mr. Z. did not, leading the landowner to lose the case. In later years Mr. Z. stopped attending services and allegedly hired others to kill Diep."
Crucially, the report states that Diep's death was not linked to Viet Minh or communist forces. At the time, the investigation notes, the movement sought to unify Vietnamese people regardless of religion, and Diep himself was not politically active.
Ms. L., a laywoman, testified that "I never saw Diep engage in political or military activity. He maintained good relationships with everyone, including the French, the Japanese, followers of the Cao Dai religion and Viet Minh, all of whom he received cordially when they visited."
Other witnesses said Viet Minh members occasionally asked Diep for food or supplies.
Fr. Peter Vu Van Hai, vicar general of Can Tho Diocese, said the findings were examined and approved by the Vatican. On Nov. 25, 2024, Pope Francis formally declared that Diep "was killed out of hatred for the faith on March 12, 1946," allowing the beatification to proceed without a verified miracle.
"This is the first time the local church has officially clarified the cause of his death," Anthony Tran Trinh Duy, a longtime devotee in the neighboring Long Xuyen Diocese, told NCR. "It ends a painful misconception and honors the truth."
Duy said the clarification carries particular weight in Vietnam, where relations between the Catholic Church and the communist state have long been shaped by suspicion and historical trauma.
By explicitly rejecting claims of communist involvement, he said, the church hopes to remove lingering political obstacles to Diep's cause and refocus attention on his pastoral legacy.
Duy said Diep's willing self-sacrifice for his people is recognized. Aware of the danger he faced, the priest continued his ministry and was killed while carrying out his priestly duties — a death the church now recognizes as martyrdom rooted in charity.
For decades, local people have referred to Diep simply as "the martyr," honoring him as a priest who gave his life to protect those entrusted to him and to uphold Christian values of love, justice and peace.
That devotion remains strong. On Jan. 3, Anna Nguyen Thi Nhuan, 80, traveled with her 15 family members from Ho Chi Minh City to the Tac Say Pilgrimage Center to mark the Vatican's approval of Diep's beatification.
Despite difficulty walking because of arthritis, she said she was deeply moved that the ceremony will be held at the very site where Diep was killed.
"I am very happy that Diep will be beatified where he gave his life," she told NCR. "His case is truly special."
Duy said he has heard countless testimonies of favors received through Diep's intercession, including healing from serious illness, help for infertile couples, family reconciliation and relief from crushing debt. Many followers of other faiths, he added, also pray at Diep's shrine.
Every year, tens of thousands of pilgrims from across the Southeast Asian country travel to Tac Say on the anniversary of Diep's death, bringing offerings such as fruits, incense, candles and even roasted pigs.
Church leaders expect similarly large crowds — including the Vietnamese diaspora — for the beatification Mass.
Loi has urged local clergy, religious and lay Catholics to assist with preparations so the celebration is held "with reverence, care and deep faith."
For Vietnamese Catholics, Duy said, Diep is more than a figure from the past. He remains a symbol of pastoral courage, solidarity with the poor and fidelity amid political violence — a witness believed to continue to resonate in Vietnam.