Gillette is on trial, accused of murdering his father James and his father's partner Anne McLucas.
Johan testified that he went to his father's home to get water on the morning of September 7, 2012.
He believed his father to be gone, and McLucas to be visiting family in Boston.
However, after being beckoned into his dad's bedroom by James Gillette, a heated discussion took place.
Johan claimed James threatened to kick him and Asia Seaton off the property.
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