If a renowned jihadi cleric can't get through to Islamic State, who can?

While the self-described Islamic State's claim that it burned 45 people to death in Iraq yesterday has yet to be confirmed, its obsession with torture and murder continues to rise. And not even a key proponent of global jihad has been able to dissuade them from such gruesome action.

Iraqi police Col. Qasim al-Obeidi said that the Islamic State burned 45 captives alive in the Anbar Province town of Baghdadi yesterday, according to the BBC. While his assertion has yet to be proved with hard evidence, the group and its online fans continue to revel in the arc of violence IS has drawn from Libya in North Africa, across to Egypt's Sinai Peninsula, and most often in Iraq and Syria.

Baghdadi fell to the Islamic State last Thursday, the first major town the group had seized in Iraq and Syria for months. The grab came after a series of reverses, most famously the loss of the ethnic Kurdish town of Kobane on the Syrian-Turkish border last month.  Baghdadi is just five miles northeast of Asad Air Base, where some 300 US Marines are now training members of the Iraqi Army's 7th Division.

The day after the town fell, IS launched a suicide attack on the gates of the base. It was repelled, but served as a reminder of the US troops now in harm's way in Iraq, and of how much IS would like to get hold of some of them.

Islamic State's obsession with extreme brutality is by now well established. Its leader, who goes by the nom-de-guerre Abu Bakr al-Baghdadi, has long since established a reputation as the Hulagu Khan of modern times, after the 13th-century Mongol leader who routinely had whole cities put to the sword.

Though the Obama administration is working hard to convince possible IS recruits that the group is un-Islamic, emerging evidence makes it clear that Baghdadi's followers aren't listening. That point is driven home by the failed efforts of Abu Mohamed al-Maqdisi, a Jordanian cleric long renowned in Al Qaeda and similar circles as a theorist and supporter of what is sometimes called global jihad. Abu Musab al-Zarqawi, who led Al Qaeda in Iraq until his death in 2006, was his former student.

Details have been coming out since late last year of how Maqdisi, who was jailed by Jordan in 2009, has worked with the authorities there to try to negotiate the release of a string of civilian captives held by IS, contacting IS members in Syria over the WhatsApp messaging system. In each case he failed. Maqdisi likewise sought to dissuade IS from kidnapping and murdering aid workers and civilians in general, an effort the group's supporters have scorned.

After Maqdisi was released from prison last summer, his first intervention was to try to save the live of Alan Henning, a British cab driver who'd left his comfortable life in the UK to become an aid worker delivering food and medical supplies to Syria's stricken towns. Henning was savagely beheaded on video in October.

The cleric was also involved in efforts to negotiate the release of Peter Kassig, an American aid worker who had converted to Islam while in Jordan. Those efforts also came to nothing in November, and Maqdisi was re-arrested, with Kassig murdered soon after. 

Maqdisi was then quietly released again in December, after Jordanian pilot Lt. Muath Kassasbeh crashed over Syria and was captured by the Islamic State. In an interview on Jordanian TV earlier this month, Maqdisi said he reached out to Baghdadi and Turki al-Binali (an IS ideologue who was also a former student of Maqdisi's), urging that the pilot be freed in exchange for Sajida al-Rishawi, an Al Qaeda in Iraq member who participated in the massacre of 57 civilians at three hotels in Amman in 2005.

One unnamed IS member did respond, and a dialogue ensued about an exchange of Kassasbeh for Rishawi. But while they negotiated, and IS continued to issue public demands, Kassasbeh was already dead, burned alive in a cage in Syria, a fact that would become clear weeks later when IS released its video tape of the grotesque murder. In his TV interview, Maqdisi called the group liars and practitioners of "evil traditions." 

The extent to which Maqdisi was being toyed with has become clear in the past few days, following IS's release of the audio of his contacts with the group. At the end of their final conversation, the jihadi he's talking to promises that a video of Kassasbeh will be provided soon, which Maqdisi took to mean a proof of life for the hostage. What came instead was the murder video.

Jordan executed Rishawi, who had been on death row since 2006, the next day.

Maqdisi is widely derided online by IS supporters, who mock him on Twitter amid their ecstatic sharing of pictures of corpses and bound men being thrown to their deaths from high roofs.

The Jordanian cleric is not exactly a warm figure. Though he emerged as a critic of Al Qaeda in Iraq, the forerunner to IS, in the past decade, his criticism was over practical matters. In his opinion, the indiscriminate slaughter of Shiites and Christians was counterproductive to the shared goal of enforcing an extreme version of Islamic law on as much of the world as possible.

But that's why this episode is interesting. If he holds no influence over IS, then who could?