JERUSALEM — A Palestinian man lured an Israeli soldier he worked with at a sandwich shop outside Tel Aviv to the West Bank on Friday, and killed him in hopes of using the body as leverage to lobby for the release of his brother from an Israeli prison, military officials said Saturday.

Lt. Col. Peter Lerner, a spokesman for the Israeli military, said the Palestinian, Nidal Omar, had confessed to the crime after being arrested with seven others early Saturday.

The closeness of the relationship between Mr. Omar, 42, and the soldier, Sgt. Tomer Hazan, 20, remained unclear late Saturday, but the owner of the shop in Bat Yam where they worked said in a television interview that both men were well liked. Colonel Lerner said Mr. Omar had persuaded Sergeant Hazan to go with him in a taxi Friday from Israel to a Jewish settlement in the West Bank and then to Beit Amin, a nearby Palestinian village of 1,100, where his family is from.

Mr. Omar then took Sergeant Hazan to an open area, killed him and hid his body in a water cistern, according to Colonel Lerner, who said Mr. Omar “wanted to barter with the dead body.” Colonel Lerner did not say how the soldier had died.