There are many explorations to the question: who the gardener was. Some people say that he was only an employee. Some others say that he was Michael’s father, who was working there only to live by the grave of Michael. And the rest even argue that he was lordd Christ himself as well. He said ‘son’ rather than ‘nephew’ while leading her to the grave.
But, I think that the gardener was the father of Michel himself. I think so only because the write says that there was infinite compassion / endless love in his eyes. Human being who have the utmost respet and value for their ones only can have such attribute. So, the gardener was Michel’s father. If it’s so, we can also guess that the he had forgiven Helen for her crime.