The term "blood curse" refers to a New Testament passage from the Gospel of Matthew, which describes events taking place in Pilate's court before the crucifixion of Jesus, and specifically the willingness of the Jewish crowd to accept liability for Jesus' death.
Pilate Washes His Hands by James Tissot – Brooklyn Museum
In the canonical gospels, Pilate's court refers to the trial of Jesus in praetorium before Pontius Pilate, preceded by the Sanhedrin Trial. In the Gospel of Luke, Pilate finds that Jesus, being from Galilee, belonged to Herod Antipas' jurisdiction, and so he decides to send Jesus to Herod. After questioning Jesus and receiving very few replies, Herod sees Jesus as no threat and returns him to Pilate.
Jesus and Pilate by William Hole
Judgment of Jesus. 1st Station of the Calvary of the Church of Nuestra Señora de la Asunción in Villamelendro de Valdavia.