Mark 15:42

‘And when evening was now come, because it was the preparation, that is the day before the Sabbath.'

Note the use of ‘paraskeue' which can mean Friday specifically or the day of preparation before a special Sabbath. Here it means Friday the day before the normal Sabbath (compare John 19:14 where it probably also means ‘the Friday of Passover week'), for if the Last Supper had been a Passover meal it would already be a special Sabbath, 15th of Nisan.

‘Evening was now come.' That is it was approaching the new day which would commence around 6:00 pm and would be the Sabbath.

It appears that Rome conceded to the Jews their demand that bodies of criminals should not be left dying or dead in the open over the Sabbath to defile the land. That is why the breaking of the legs of the two insurrectionists took place so as to hasten their deaths (John 19:32), in order that the bodies could be removed before the commencement of the Sabbath at around 6:00 p.m. This followed the requirements of Deuteronomy 21:22 and Joshua 8:29 that the bodies of executed criminals who have been hanged on a tree should not remain there overnight lest they defile the land. According to Josephus this law was interpreted in the first century in such a way as to cover the bodies of those who had been crucified. The normal Roman practise would have been to leave the bodies on the crosses, to serve as a warning to other would-be offenders.