The inquiry into the sainthood cause of Fr. Walter Ciszek, S.J., a missionary who was imprisoned in the Soviet Union for 23 years, has taken a "major step forward" with the Vatican's Congregation for the Causes of Saints issuing a declaration that the investigation is valid.

"This breakthrough in the process is very encouraging and a testimony to the commitment and dedication of all those involved," Bishop John Barres of Allentown said March 19.

The Diocese of Allentown's investigation into the priest's life, virtues and reputation for sanctity is valid, the congregation declared. The congregation transferred responsibility for the cause to the Diocese of Allentown from the Byzantine Catholic Eparchy of Passaic, N.J., in 1996.

The diocese's inquiry into Fr. Ciszek's reputation for holiness collected materials and documentation, including testimony from 45 witnesses. It also gathered the priest's published and unpublished works and forwarded them to Rome in 2006. At the congregation's request, in 2011 it sent additional documentation from the Father Ciszek Center in Shenandoah and from the Jesuit archives in the U.S. and Rome.

"This is a major step forward in the effort to see Fr. Ciszek canonized as the saint of the Church," Matt Kerr, the Diocese of Allentown communications director, told EWTN News March 20.

"Fr. Ciszek grew up in Shenandoah, in a small town upstate here. The church where he was baptized is still an active church in the diocese."

The ruling means that the focus of the cause now shifts from the local diocese to Rome.

Msgr. Anthony Muntone, the diocesan co-postulator for Fr. Ciszek's canonization cause, said the next phase of the process involves a presentation from the Roman postulator, the writing of a biography, and the compilation of the information proving Fr. Ciszek's heroic virtue.

Nine theologians will then examine the information to determine whether the priest heroically exhibited the theological virtues of faith, hope and charity and the cardinal virtues of prudence, justice, fortitude and temperance.

If the theologians agree that Fr. Ciszek's life showed heroic virtue, they will recommend his cause to the bishops and cardinals of the Congregation for the Causes of Saints to study. If that congregation approves, Pope Benedict XVI will receive the results of the inquiry and decide whether to declare Fr. Ciszek "venerable."

Upon papal approval, Fr. Ciszek's cause will then investigate any claims of miracles before he can be officially recognized as a saint.

Fr. Ciszek was born in 1904 in Shenandoah, Pennsylvania. He entered the Jesuit novitiate in 1928 and was ordained in 1937, after being trained to say Mass in the Russian rite.

After two years in Poland, he used the chaos of World War II as cover to enter the Soviet Union so that he could minister to Christians who lived under Communist persecution.

He was arrested by the Soviet authorities as a supposed spy in 1941. His imprisonment included torturous interrogation, solitary confinement and years of hard labor near the Arctic Circle. Despite the dangers, he said Mass in secret and heard the confessions of other prisoners.

When he was not imprisoned, he also ministered to several parishes.

The priest was returned to the U.S. in a spy exchange in 1963.

He recounted his trials and reflected on their spiritual meaning in his popular memoirs "He Leadeth Me" and "With God in Russia."

Fr. Ciszek died at Fordham University in New York on Dec. 8, 1984.