An art historian. Note: Not any kind of scientist or theologian or biblical archaeologist. An art historian.
With an imagination. And a hypothesis based on his imaginings.
According to de Wesselow, there's no need to invoke a miracle when simple chemistry could explain the imprint. It's likely, he says, that Jesus' female followers returned to his tomb to finish anointing his body for burial three days after his death. When they lifted the shroud to complete their work, they would have seen the outline of the body and interpreted it as a sign of Jesus' spiritual revival.
From there, de Wesselow suspects, the shroud went on tour around the Holy Land, providing physical proof of the resurrection to Jesus' followers. When the Bible talks about people meeting Jesus post-resurrection, de Wesselow said, what it really means is that they saw the shroud. He cites the early writings of Saint Paul, which focus on a spiritual resurrection, over the gospels of Mark, Matthew, Luke and John, which were written later and invoke physical resurrection.