During a service in Rome on Saturday evening, the pontiff held the hands of the Roselyne Hamel, the brother of 85 year old Fr Jacque Hamel.
Ms Hamel had just told others gathered at St Bartholomew Basilica on Tiber Island her brother was killed by "two youths radicalised by a discourse of hate".
In his homily, Pope Francis touched upon the hardship experienced by refugees, lamenting that "international accords seem more important than human rights".
Hamel was celebrating Mass at his church in Normandy on 26th July when two 19 year old men stormed in and slit his throat.
The perpetrators, Adel Kermiche and Abdel Malik Petitjean, were shot dead by French police as they left the church in Saint-Étienne-du-Rouvray.