JERUSALEM — The slightly plump Israeli teenager on the witness stand insisted that he had not known the plan was to kill, and had “never dreamed” it would end that way.

The teenager, a second youth and one adult, Yosef Haim Ben-David, 30, are on trial in Jerusalem District Court, charged with the abduction and premeditated murder of a Palestinian teenager, Muhammad Abu Khdeir. He was snatched off a street near his East Jerusalem home, driven to a forest, beaten unconscious and burned to death in the early hours of July 2, 2014.

A year later, a final chapter of that traumatic period is playing out with agonizing intimacy in a cramped courtroom where the three defendants, who are all related, and the parents of the victim sit a few yards apart.

Under a court order, the two teenage defendants’ names cannot be published because they are minors. At the time of the crime they were 16, the same age as Mr. Abu Khdeir.