There where Two Sabbaths on the week of the execution of Jesus.. The first was on the 15th of nissan called the first day of unleaved bread,, This Sabbath started on wednesday sundown and went to thursday sundown.. Jesus remained in the toimb untill sundown saturday which was the end of the Normal weekly Sabbath..
Mark's third hour was when Jesus was crucifed Not when He actually died.. Crucified meaning being nailed to a cross.. we read..
(Mark 15:25-34) "And it was the third hour, and they crucified him. {26} And the superscription of his accusation was written over, THE KING OF THE JEWS. {27} And with him they crucify two thieves; the one on his right hand, and the other on his left. {28} And the scripture was fulfilled, which saith, And he was numbered with the transgressors. {29} And they that passed by railed on him, wagging their heads, and saying, Ah, thou that destroyest the temple, and buildest it in three days, {30} Save thyself, and come down from the cross. {31} Likewise also the chief priests mocking said among themselves with the scribes, He saved others; himself he cannot save. {32} Let Christ the King of Israel descend now from the cross, that we may see and believe. And they that were crucified with him reviled him. {33} And when the sixth hour was come, there was darkness over the whole land until the ninth hour. {34} And at the ninth hour Jesus cried with a loud voice, saying, Eloi, Eloi, lama sabachthani? which is, being interpreted, My God, my God, why hast thou forsaken me?"