Speech analysis could help ID executioner in new ISIS video

Now, ISIS has introduced a new English-speaking executioner, and his accent is causing many to take note.

He appears on a beach on the coast of Libya, dressed in tan fatigues and positioned at the center of over dozen black-clad militants leading an equal number of hostages -- Egyptian Coptic Christians they ultimately decapitate brutally in front of the camera.

As with previous ISIS videos, the intelligence community will be examining the footage to see what forensic clues can be gleaned about the speaker -- his height, his build, his choice of words -- all of these will be analyzed to determine who he could be.

But perhaps the most intriguing clues could be found in his voice. His English appears to be near-fluent, with an accent that might be American or Canadian.

CNN reached out to linguists in the U.S. and Canada who have seen the video to better understand what investigators may be noticing in the speaker's speech patterns.

Several common elements stood out in their analyses.

Most of the linguists heard traces of Arabic influence in the speaker's dialect -- indicating he is likely bilingual. But they differed on where and when the speaker most likely learned English.

Erik Thomas, a sociophonetics researcher at North Carolina State University, told CNN the speaker "definitely learned his English in the United States," though he also demonstrates some foreign language influence, likely Arabic.

"It's hard to say which he learned first," said Thomas, but he likely learned English from an early age.

Based on speech patterns, Thomas said the English is more American than Canadian, and probably does not come from the east coast, urban south or southern midwest.

"It's remotely possible but highly unlikely that he learned his English in a foreign location," Thomas said about the possibility he learned English in North Africa or the Middle East. "His accent is just too good. Very few people can learn a second language that well if they weren't immersed in it."

University of Georgia professor Bill Kretzschmar, who authored the book "The Linguistics of Speech," believes English is probably the speaker's second language, but agrees that it was likely acquired "either in North America or from a North American teacher."

"The speaker may have English as a second language because the intonation is not quite fluent in the way you would expect of a native U.S. speaker or native Canadian," Kretzschmar said. "But the speaker may have spent a long time in North America, because the speech is really too fluent just to have been learned abroad."

"The English he learned is not a British variety," West Virginia University linguist Kirk Hazen said. "He has his Rs at the ends of syllables."

"But," Hazen said, "he could have learned English in Turkey or lots of other places and learned a non-British variety."

There are a number of American schools and universities in the Middle East and North Africa, as well as other places in the world.

"The speaker is obviously a native speaker of Arabic, given the way he speaks that language and the influence it has on his English" said another linguist, Charles Boberg of McGill University in Montreal. "But his English is extremely fluent, to a level I would label near-native."

"Its regional characteristics indicate that it was acquired in North America," Boberg said, "probably in middle to late childhood, early enough to have little trace of the sort of 'foreign' accent you would hear in true second-language English, acquired by an adult immigrant, but not early enough to acquire the truly native characteristics of any particular regional variant of North American English, as we would hear in the speech of someone who was born in North America."

In part due to the short length of the video, none of the linguists CNN spoke with could make definitive conclusions about the speaker's background, but offered their analysis as likely scenarios.

The individual in question speaks for just under a minute and addresses the camera directly, most of his face obscured by a ski mask.

"Some of what is going on with his speech style is that this performance is a religious genre and a memorized script," said Hazen.

(CNN)