HEBRON, West Bank — Three weeks into Israel's offensive in the Gaza Strip, Israeli security officials are no closer to finding the men held responsible for the killings that sparked the assault, and some of those working on the case are strongly rejecting the Israeli government's assertion that the alleged killers were linked to the militant group Hamas.

Israel has failed to capture Marwan Qawasmeh, 29, and Amar Abu Aisha, 32, the two men it says were behind the murder of three Israeli teens on June 12. At least four of the men's relatives have been detained over the last month in connection to the kidnapping and killing. They remain under gag order, meaning they cannot be made public or reported on inside Israel.

In the weeks following the kidnapping, Israeli Prime Minister Benjamin Netanyahu said that Israel knew "for a fact" that Hamas was behind the kidnapping, adding, "Hamas is responsible, and Hamas will pay."

But one Israeli intelligence officer who works in the West Bank and is intimately involved in investigating the case spoke to BuzzFeed on condition of anonymity and said he felt the kidnapping had been used by politicians trying to promote their own agenda.

"That announcement was premature," the intelligence officer said. "If there was an order, from any of the senior Hamas leadership in Gaza or abroad, this would be an easier case to investigate. We would have that intelligence data. But there is no data, so we have come to conclude that these men were acting on their own."

Israeli police spokesman Micky Rosenfeld told the BBC last week that police believed the killers did not have ties to Hamas in Gaza — but did to Hamas in the West Bank. But the Israeli intelligence officer noted that the Shin Bet, Israel's internal security agency, and Israeli intelligence are the ones taking the lead on the investigation, not the police.

Like other Israeli military officials, the officer said he was worried that events on the ground had been misrepresented by politicians. Netanyahu has long been pressed by more right-wing elements of his government to address Hamas' growing popularity in the West Bank. In the month prior to the kidnapping, Israel had strongly lobbied against Hamas joining together in a unity government with the Palestinian Authority in the West Bank — a move that brought Hamas into the fold of political life there and could, one day, allow its elected officials to openly campaign in the West Bank. "Hamas in the West Bank is fragmented, there are many factions — could these teens have broken off and called themselves a separate Hamas faction? Possibly. But that is not the most likely scenario, nor the one we are pursuing," the officer said.

Former Shin Bet Chief Yuval Diskin, who long oversaw Israel's security operation in the West Bank, recently told Der Spiegel he did not believe Hamas was behind the kidnapping.

"Hamas didn't want this war at first either. But as things often are in the Middle East, things happened differently. It began with the kidnapping of three Israeli teenagers in the West Bank. From what I read and from what I know about how Hamas operates, I think that the Hamas political bureau was taken by surprise. It seems as though it was not coordinated or directed by them," said Diskin.