Story highlights A forensic audio expert says at least 10 shots are fired in the recording

Lawyer: The FBI questioned a man whose audio might contain the Michael Brown shooting

The audio was recorded during a video chat with a friend

CNN cannot independently confirm whether the shots heard were from the Brown incident

Could a newly released audio provide more clues on what led up to Michael Brown's shooting death

The FBI has questioned a man who says he recorded audio of gunfire at the time Brown was shot by Ferguson, Missouri, police on August 9, the man's attorney told CNN.

In the recording, a quick series of shots can be heard, followed by a pause and then another quick succession of shots.

Forensic audio expert Paul Ginsberg analyzed the recording and said he detected at least 10 gunshots -- a cluster of six, followed by four.

"I was very concerned about that pause ... because it's not just the number of gunshots, it's how they're fired," the man's attorney, Lopa Blumenthal, told CNN's Don Lemon. "And that has a huge relevance on how this case might finally end up."

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The man, who asked that his identity not be revealed, lives near the site of the shooting and was close enough to have heard the gunshots, his attorney said.

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Photos: The funeral of Michael Brown Photos: The funeral of Michael Brown Michael Brown's casket arrives at St. Peter's Cemetery on Monday, August 25, 2014 for his funeral. Brown, 18, was shot and killed by police Officer Darren Wilson on August 9 in Ferguson, Missouri. Brown's death sparked protests in the St. Louis suburb, and a national debate about race and police actions. Hide Caption 1 of 17 Photos: The funeral of Michael Brown Michael Brown Sr. yells out as the casket holding the body of his son, Michael Brown, is lowered into the ground during his funeral service in St. Louis. Hide Caption 2 of 17 Photos: The funeral of Michael Brown Family members touch the copper top of the vault containing Brown's casket. Hide Caption 3 of 17 Photos: The funeral of Michael Brown Mourners fill the pews for the funeral service at Friendly Temple Missionary Baptist Church in St. Louis. Hide Caption 4 of 17 Photos: The funeral of Michael Brown Lesley McSpadden, Brown's mother, sits during the funeral. Hide Caption 5 of 17 Photos: The funeral of Michael Brown The Rev. Al Sharpton speaks during the funeral. Hide Caption 6 of 17 Photos: The funeral of Michael Brown A Brown family member wears a tie with Michael Brown's face on it. Hide Caption 7 of 17 Photos: The funeral of Michael Brown People sing during the funeral for Brown. Hide Caption 8 of 17 Photos: The funeral of Michael Brown Brown's casket sits inside Friendly Temple Missionary Baptist Church in St. Louis before the start of his funeral. Hide Caption 9 of 17 Photos: The funeral of Michael Brown Funeral attendees sing before the start of the service on August 25. Hide Caption 10 of 17 Photos: The funeral of Michael Brown Brown's mother, Lesley McSpadden, arrives at Friendly Temple Missionary Baptist Church for the funeral service. Hide Caption 11 of 17 Photos: The funeral of Michael Brown Brown's father, Michael Brown Sr., arrives for the funeral. Hide Caption 12 of 17 Photos: The funeral of Michael Brown Funeral attendees raise their hands as they wait in line to enter the church on August 25. Hide Caption 13 of 17 Photos: The funeral of Michael Brown Filmmaker Spike Lee takes a picture of a St. Louis Cardinals baseball cap that rests on top of Brown's casket. Hide Caption 14 of 17 Photos: The funeral of Michael Brown Mourners wait in line to enter the church. Hide Caption 15 of 17 Photos: The funeral of Michael Brown A hearse sits outside the church before the funeral. Hide Caption 16 of 17 Photos: The funeral of Michael Brown James Wright waits for the Friendly Temple Missionary Baptist Church to open for the funeral service. Hide Caption 17 of 17

He was speaking to a friend on a video chat service and happened to be recording the conversation at the same time Brown was shot, Blumenthal said.

The attorney said she learned of the man's recording late last week from a mutual friend.

"I had to get his consent before I could reach out to the FBI," Blumenthal said.

CNN cannot independently verify the authenticity of the tape and has asked the FBI for confirmation of their interview with the man who made the recording.

The meaning of the pause

It's difficult to prove from the audio why the pause took place or whose narrative it supports.

Attorney Chris Chestnut said he was surprised by the gap in shots.

"It's the pause that gives most concern in a police shooting, especially with an unarmed victim, because at this point Mr. Brown is defenseless -- he has no weapon," said Chestnut, who represented the family of Jonathan Ferrell

Like Brown, Ferrell was an unarmed African-American man who was shot and killed by a white police officer.

But if the gunfire heard on the audio is indeed from the Brown incident, the pause doesn't automatically suggest wrongful intent by the officer.

"To be fair, there could be other explanations for that pause," said attorney Van Jones, co-host of CNN's "Crossfire." "Maybe the officer will say, 'Well, I fired and he kept advancing, so I fired again.' "

Witnesses and a friend of Officer Darren Wilson have given conflicting accounts of what led up to Brown's death.

Dorian Johnson, a friend of Brown's who was walking with him at the time of the shooting, said the officer shot Brown once by the police car and again as he ran away.

According to Johnson, Brown was struck in the back and then turned around and put his arms up as the officer kept shooting.

But a woman who identified herself as a friend of Wilson called into a St. Louis radio show last week with what she said was the officer's version of events. The caller, who identified herself only as "Josie," said Brown taunted the officer and charged at him. Her account accurately matches what Wilson has told investigators, a source with detailed knowledge of the investigation told CNN.

An autopsy showed that all the entry wounds were in the front of Brown's body.

Key witness speaks out

Ferguson police said Brown allegedly robbed a convenience store shortly before the shooting.

And reports that his friend Johnson had a criminal record that includes lying to police has put Johnson's credibility in question.

In 2011, Johnson was arrested and accused of theft and lying to police about his first name, age and address.

Johnson said Monday night he doesn't understand why some are questioning his credibility.

"I see they bring up my past, my history, but it's not like it's a long rap sheet," Johnson told Lemon. "This one incident shouldn't make me a bad person."