This is Part one in a series on the Resurrection accounts as recorded in the gospels
Dating: Between A.D. 55 and A.D. 70
Author: Possibly, but not conclusively, John Mark (not one of the 12 disciples, but aid and interpreter to Peter; accompanied Paul at least part of the way on his first missionary journey).
When the Sabbath was over, Mary Magdalene, Mary the mother of James, and Salome bought spices so that they might go to anoint Jesus’ body. Very early on the first day of the week, just after sunrise, they were on their way to the tomb and they asked each other, “Who will roll the stone away from the entrance of the tomb?”
But when they looked up, they saw that the stone, which was very large, had been rolled away. As they entered the tomb, they saw a young man dressed in a white robe sitting on the right side, and they were alarmed.
“Don’t be alarmed,” he said. “You are looking for Jesus the Nazarene, who was crucified. He has risen! He is not here. See the place where they laid him. But go, tell his disciples and Peter, ‘He is going ahead of you into Galilee. There you will see him, just as he told you.’”
Trembling and bewildered, the women went out and fled from the tomb. They said nothing to anyone, because they were afraid.
Irenaeus wrote (Against Heresies 3.1.1): “After their departure [of Peter and Paul from earth], Mark, the disciple and interpreter of Peter, did also hand down to us in writing what had been preached by Peter.” Note that Irenaeus had read Papias, and thus Irenaeus doesn’t provide any independent confirmation of the statement made by the earlier author.
It is debatable whether or not the writing was begun before or after the death of Peter. If it was before, it was only shortly before. So the record of this gospel would have been, most likely, from the memory of the writer who was not an eyewitness on the hearsay of Peter who was an eyewitness some 25 to 50 years after the actual events. Peter’s death is marked around 67 A.D. and John Mark’s is marked around 68 A.D. 
The Gospel of Mark was the first gospel written. That Irenaeus had read Papias is not a definite indicator of the writer of this gospel account. Since Papias writings are circa 90-120 A.D. it is unlikely he was living at the time of the writing. Papias does provide the earliest testimony in writing to the author of the Gospel of Mark based on oral tradition.
If I’m understanding correctly: even if it’s given that John Mark wrote Mark, what we have is the writing from memory of a non-eyewitness based on the recollection of Peter years after the events, attested to by Irenaeus who lived in the next century, based on his reading of Papias based on oral tradition testifying to the veracity of the authorship of the Gospel of Mark.
According to Christianity we are to trust that this account is accurate without the benefit of any original documents because the Holy Spirit has kept it safe from error, embellishment, and fabrication of it’s content.
*ETA: I am open to correction and/or other information on the dating/veracity of authorship of the Gospel of Mark.