Congressman Michael McCaul said that other potential threats are being monitored "very closely."
The prisoners were released as gesture of goodwill before the pope's arrival.
On Tuesday, the pope will release decrees to reform the marriage-ending process.
Catholic women denied the right to enter the clergy are taking matters into their own hands.
Meanwhile, Israel debates its response to refugee crisis.
New polling by Pew Research Center shows Catholic attitudes on key social issues are increasingly liberal.
Ahead of his announced Holy Year of Mercy, the pope wrote about "the tragedy of abortion."
Paraguayan law permits abortion if a mother's life is endangered. Pope Francis last year called abortion "horrific," and has shown no signs of changing the Catholic Church's position.
Environmentalists say Ecuador's leftist leader, Rafael Correa, gives a greater priority to business.
The pope puts it very plainly to leaders who might be laggards: It’s time to face climate change.
In what Vatican officials are calling "a heinous act," the Italian magazine "L'Espresso" leaked a draft of the hotly anticipated papal encyclical on the environment.
The creation of the tribunal is the biggest step the Vatican ever has taken to hold bishops accountable.
The pope apparently never even saw an episode of "Friends."
Faced with an onslaught of questions, the Vatican rebutted what it called erroneous media reports.
The move highlights Pope Francis' drive to help embattled Christian communities in the Middle East.
The masterpiece of society is the family: the man and the woman who love each other," the pope said.
Bishop Robert Finn of the Catholic diocese of Kansas City-St. Joseph tendered his resignation last week.
Pope calls the massacre of up to 1.5 million Armenians 100 years ago "the first genocide of the 20th century," prompting Turkey to accuse him of inciting hatred.
"I hope the international community does not look on, mute and inert, at such an unacceptable crime," Francis said.