A forensic analysis for the FBI found “absolutely no evidence of tampering” with video from a Burger King near the scene where Laquan McDonald was gunned down by Chicago Police Officer Jason Van Dyke last year on the South Side, a source close to the investigation said Monday.

An 86-minute gap in the Burger King tape and the fact that police officers spent about two hours at the restaurant on the night of the shooting trying to retrieve the video is fueling speculation about a police conspiracy to erase that portion of the tape.

“The district manager told us it was deleted,” said Jeffrey Neslund, an attorney for the McDonald family. “It is curious that there were 86 minutes missing. We don’t know for a matter of certainty what happened to the Burger King video, but we know what the employees told us.”

But a source close to the investigation said the FBI had the Burger King video “forensically analyzed.” 

“They looked at it and found absolutely no evidence of any tampering or any removal of any portion of the tape,” the source said.

“That system that Burger King has is a mess and it would break down in the weeks and months before this incident. There were major gaps everywhere,” the source added.

Why, then, did the officers spend nearly two hours at the Burger King?

“They were trying to get to the video to see if it captured anything. They weren’t trying to delete anything. . . . All that tape would show is [McDonald] running around before the shooting. There was no reason for them to tamper with it,” the source said.

The FBI analysis helps explain why Cook County State’s Attorney Anita Alvarez and Chicago Police Supt. Garry McCarthy virtually ruled out police tampering last week on the day Van Dyke, who is white, was charged with first-degree murder for shooting McDonald, who is black.

“We have looked at those videos . . . and it doesn’t appear that it’s been tampered with,” Alvarez said on that day. McCarthy said on that same day that reports of tampering were “absolutely not true. And I think the state’s attorney addressed that. There were apparently technical difficulties. But in no way, shape or form is there any evidence that anything was tampered with.”

Conspiracy theories are also being fueled by reports that witnesses who saw Van Dyke unload 16 rounds into the McDonald’s body were turned away by at least five other officers at the scene.

Neslund, the attorney for the McDonald family, said other witnesses were taken to a police station “and told over a period of hours to change their stories.”

The 86-minute segment of missing video could have shown witnesses’ reactions to the shooting and their later interactions with police, Neslund said.

But the source said the Independent Police Review Authority spent about a week interviewing witnesses after McDonald’s death before referring the case to the state’s attorneys’ office — and found no evidence anybody was turned away.

“Witnesses have been interviewed and told investigators what they saw. We’ve had nobody come and say, ‘I was there and they chased me away.’ People are seeing [a conspiracy] under every tree,” the source said.

IPRA has suspended its administrative investigation pending the outcome of the joint state and federal investigation. When the IPRA investigation resumes, sources said it will examine two other issues: Why none of at least five other police officers who arrived at the scene offered medical assistance to McDonald and why none of the dashboard camera videos had any working audio.

“With 16 shots, officers may argue that McDonald was too shot up to bother. But somebody should have gone over to check on him. They called an ambulance quickly and the ambulance got there while he was still alive. So somebody should have gone to check on him,” the source said.

Last week, McCarthy said there was “no audio to my knowledge with any of the video that was taken” on the night McDonald was killed. The superintendent acknowledged that’s a break from police protocol. “Sometimes we have technical difficulties. Sometimes officers need to be disciplined if they don’t turn it on at the right circumstance,” McCarthy said.

When it resumes, the IPRA investigation will determine whether those microphones were turned off deliberately or, if there was a malfunction, whether there was a “repair ticket” on those faulty microphones, the source said.