Egypt's president has promised that investigators will work "night and day" to locate and prosecute those responsible for the torture and death of an Italian student, insisting that the crime must not harm Egypt's relations with Italy.

President Abdel-Fattah el-Sissi gave an interview to Italian daily La Repubblica, published Wednesday, in which he directed a message to the family of Giulio Regeni. Regeni went missing Jan. 25, the fifth anniversary of the 2011 uprising when police were deployed across Cairo. Regeni's body was found nine days later bearing signs of torture.

In his first public comments about the case, El-Sissi said: "I promise you that we will arrive at the truth, that we will work with Italian authorities to bring justice and punish the criminals who killed your son."