"He has said that going to jail, for him, is a chance to convert people and baptise them," Fr Ly's older brother Nguyen Hoang An told the Perth Record.
Vietnamese prisons do not allow inmates to be visited by priests, An told The Record through an interpreter. An has lived in Australia since 1983 but speaks little English.
An said that during Fr Ly's long years in jail he has converted many prisoners and prison guards to the Catholic faith.
Fr Ly, who has already spent 14 years in Vietnamese prisons - much of it in solitary confinement, was recently sentenced to eight more years in jail.
Fr Ly and four pro-democracy lay Catholic activists were jailed after speaking against Vietnam's one-party government.
Though there has been speculation about the mental effect such intense incarceration might have had on Fr Ly, An said his brother is mentally strong and that his frequent prayer to God while in jail acts as a preventative against mental deterioration.
An said he did not believe that his brother would be subjected to torture in his current imprisonment, but he said torture has been a regular feature of the prison system in Vietnam.
An, who has spent time in prison, described the psychological and physical tortures used for decades on ordinary, noncriminal Vietnamese who have run afoul of the communist regime.
"They torture you in many ways," he said. "They use two lights, very bright, and you have to look into it. Soon your brain goes blank. They don't let you eat.
"They make you stand with your hands on the wall, and if you happen to kneel down or drop that pose, they will hit you," he said.
"Then when you're too frightened, you will say everything that they want you to say," said An. "They write your supposed confession and, in that state of mind, you sign whatever they have written for you."
An has called for Australia and other countries to impose sanctions on Vietnam until the country makes progress on human rights. The Vatican, Amnesty International, and American and Australian political leaders have publicly denounced the priest's imprisonment.
However, Vietnam and the Vatican are pushing ahead with plans to establish diplomatic relations after a Vatican delegation visit of Vietnam last month.
Jailed Vietnamese priest accepts suffering as witness to Catholic faith, brother says (Catholic Online, 19/4/07)
LINKS (not necessarily endorsed by Church Resources)
Fr Thadeus Nguyen Van Ly (Amnesty International, 7/01)
Australia Vietnam Human Rights Committee
Roman Catholic Church in Vietnam (Wikipedia)
Progress and Struggle for Vietnam's Catholics (Washington Post, 23/6/05)
Eight years jail for Vietnamese priest (CathNews, 2/4/07)
Benedict visit on cards for Vietnam (CathNews, 13/3/07)
Vietnamese democracy priests arrested (CathNews, 21/2/07)
Vietnam PM in first Vatican visit (CathNews, 24/1/07)
Vietnam releases dissident priest (CathNews, 23/2/05)
Vietnamese freedom fighter priest arrested again (CathNews, 21/5/01)
20 Apr 2007