In a letter sent to the family of a U.S. journalist killed by ISIS last week, Pope Francis assured his closeness, and prayed for reconciliation and peace throughout the world.

"The Holy Father, deeply saddened by the death of James Wright Foley, asks you kindly to convey his personal condolences and the assurance of his closeness in prayer to James' loved ones," the letter states.

Signed by Vatican Secretary of State Pietro Parolin, the letter was read aloud on Sunday during a memorial Mass for Foley, which was held at the family's Catholic parish, Our Lady of the Holy Rosary Church in Rochester, N.H.

Continuing, the letter states that Pope Francis "commends James to the loving mercy of God our Father, and joins all who mourn him in praying for an end to senseless violence and the dawn of reconciliation and peace among all the members of the human family."

"Upon the Foley family, and upon his friends and colleagues, he invokes the consolation and strength borne of our hope in Christ's Resurrection."

On Aug. 19, the Islamic State (ISIS), a militant group that controls territory in Syria and Iraq, released a graphic video entitled "A Message to America," that shows the beheading of Foley, who was abducted in Syria in 2012. U.S. officials have confirmed the authenticity of the video.

Members of ISIS have stated that Foley's execution was an act of retaliation for U.S. airstrikes against Islamic State forces in Iraq, and warned that they have another missing American journalist in captivity, Steven Joel Sotloff, saying that his life depends on U.S. President Barack Obama's actions.

Pope Francis also made a personal phone call to Foley's family offering his condolences, which was confirmed by Vatican spokesman Fr. Federico Lombardi in an Aug. 21 email to CNA.

Previously detained for six weeks in Libya in 2011, James Foley wrote a letter to his alma mater, Marquette University, a Catholic university in Wisconsin, revealing how he turned to prayer, specifically the Rosary, during his captivity, and how the prayers of family and friends also gave him strength.

"I began to pray the Rosary," he wrote. "It was what my mother and grandmother would have prayed. I said 10 Hail Mary's between each Our Father. It took a long time, almost an hour to count 100 Hail Mary's off on my knuckles. And it helped to keep my mind focused."

When he was first allowed to call home after more than two weeks in captivity, Foley said his mother told him about the prayers others had offered up for him. This news made him wonder if instead of his own prayers, "it was others' prayers strengthening me, keeping me afloat."

"If nothing else, prayer was the glue that enabled my freedom," Foley said, "an inner freedom first and later the miracle of being released during a war in which the regime had no real incentive to free us."

According to the Daily Mail, Foley's parents have voiced gratitude for the prayers offered for their son and the entire family.

"We thank God for the gift of Jim. We are so, so proud of him," said his mother, Diane, adding that they prayed to God for strength and were grateful that "God has given us so many prayers" throughout James' captivity.

"Jim would never want us to hate or be bitter. We're praying for the strength to love like he did," she said.

"It's not difficult to find solace in this point in time," added his father, John. "We know he is in God's hands, and we know he's done God's work."

"We need the courage and prayers now to continue without him."