JERUSALEM — An Israeli human rights group on Monday challenged the military’s account of an episode in which a soldier shot and killed a Palestinian youth who had hurled a rock at the soldier’s vehicle, saying that video and witnesses’ accounts contradicted the army’s version of the incident.

The rights group B’Tselem, which made the assertions, also questioned Israel’s ability to impartially investigate allegations that its armed forces had acted illegally.

Immediately after the shooting on July 3, a military spokeswoman said that Israeli soldiers first fired into the air to warn the stone throwers to stop, and that the episode was under investigation. The military has since said it could not comment more on the matter.

But the video and the witnesses’ accounts appear to indicate that the soldiers ran after the youth, Muhammad Hani al-Kasba, after he threw a rock at their vehicle and that they were not in apparent danger while pursuing him, B’Tselem said. In addition, Mr. Kasba, 17, was shot in the back and the side of his face, suggesting that he was shot while fleeing the soldiers, said Sarit Michaeli, a spokeswoman for B’Tselem.