GAZA — Days after Israel's "elimination" of four senior Hamas commanders, the "hunt for traitors" is in full swing inside the Islamic organization. At least 24 suspected "collaborators with Israel" have already been executed, but the hunt continues.

The same happened for several weeks in 2009, immediately after Operation Cast Lead. It led to the hasty trials of 32 supposed "traitors," among them a 15-year-old. In 2012, shortly after Israeli forces killed Ahmad Jabari, operational commander of the Hamas armed wing known as the al-Qassam Brigades, several other people were shot dead. The body of one of them was dragged at full speed through the streets of Gaza City by a motorbike.

The "eliminations" carried out in the last days of the recent Operation Protective Edge, in particular the assassination of Hamas financial chief Muhammad al-Ghoul — killed Sunday in an airstrike — demonstrate that Shin Bet (Israel’s interior security agency) and Aman (its military intelligence) have access to first-hand information. These are collected by technological means, but also by collaborators on the ground.

Since the Six-Day War in 1967, Shin Bet has been recruiting thousands of well-integrated Palestinians who know their environment, but only a few dozen have been discovered. "Generally, those that Hamas brands as 'traitors' before shooting them dead in public are not part of our informants because they are always where nobody expects them to be," explains Lior Akerman, a former Shin Bet senior official. "They have first-hand tips and they're generally beyond suspicion."

In the early 1980s, in addition to the "moles" who infiltrated Palestinian organizations, some 2,000 machtapim (Hebrew for collaborators) operating in the Gaza Strip were among the "Village Leagues," a sort of militia that acted as a stand-in organization for the occupying authorities by engaging in trafficking and extortions.

But why do these Palestinians choose to become collaborators? "Because I prefer democracy to terrorism," replies 36-year-old Soufian (not his real name). This short black-haired man is a former hoodlum from the region of Nablus, in the West Bank, having left his parents' home when he was a teenager. Now retired, he claims to have helped the Israeli army arrest wanted Hamas leaders and "saved lives" by preventing attacks. "It's true that I was paid for it," he says. "But I put my life in danger for years. Compared to that, money doesn't mean anything."

Soufian is mum about how he was recruited. But the circumstances suggests that Shin Bet intervened to have an Israeli criminal investigation against him dropped. In exchange for his services, of course.

Palestinian and Israeli human rights organizations regularly denounce alleged Shin Bet blackmail against vulnerable Palestinians as a means of obtaining information. Among those targeted are also Gazans who wish to apply to foreign universities, relatives of prisoners who want to be able to visit them in Israeli jails, or others who with loved ones in need of hospital treatment.

Some Palestinians also claim to have been contacted directly by phone, and even by email or Facebook. And yet, the sources "fished" in that manner or by coercion are rarely reliable. "They always drop you the first chance they get, even if you give them money," says "Captain Danny," a former Shin Bet officer turned private detective in Tel Aviv.

"Of all the collaborators I had to deal with, the most efficient were those who acted in full knowledge and were not greedy. Of course, they betrayed their relatives and loved ones for money, but they were no mercenaries. They knew what they were doing and were aware of the risks."