Day of death

Tradition holds that the Last Supper took place on the first night of Passover, which is defined in the Torah as occurring after the day of the 14th of Nisan (Lev 23:5-6). In the Biblical calendar, a new day begins after sunset, rather than at midnight as in the modern western calendar. However, in order to determine the Gregorian date of Jesus' death, one needs to know the year, because the 15th of Nisan – corresponding to one of the first two full moons after Vernal Equinox – can occur on any date in late March or April in the western calendar.
All Gospels agree that Jesus died and was taken off the cross on the day before the Jewish sabbath (Friday before sunset), around the time of Passover, (the Jewish calendar counts the day as beginning with the evening). However, before the year 500, the calendar was changed yearly to align with astronomical observations. Therefore, it is not possible to state on which day of the week the 14 of Nisan occurred for any year before 500 without historical documents that attest to a particular day of the week.
More precise calculation of Jesus' date of death is complicated by apparent inconsistencies in the reports in the Synoptic Gospels as compared to the Gospel of John. In the Synoptic Gospels, the Last Supper is generally interpreted to be the Passover meal. In this case Passover would have started on Thursday night. This is highly problematic from a historical standpoint — the first day of Passover is a holy day for Jews, during which no work can be performed and many rituals of Shabbat are observed, so many events described by the Gospels (particularly, the trial and the execution) could not have taken place.
According to John, however, the Passover meal was to be eaten on the last evening before Jesus was crucified, so that the Last Supper was eaten on the evening of the 14th of Nisan[16] and the crucifixion was on the 14th during the following daylight, with Jesus dying approximately at the same time that the lambs for the Passover were being slaughtered in Herod's Temple of Jerusalem — around 3 PM ("at the ninth hour"), so that the Jews could celebrate the Passover that evening