A private investigator has been unable to find the only eyewitness to the sudden death of media innovator and conservative activist.

The apparent disappearance of Christopher Lasseter, who says he saw Breitbart drop to the sidewalk in front of a restaurant, adds to the mystery surrounding Breitbart's March 1 death.

On the day the Los Angeles County coroner released Breitbart's autopsy report, a photographic technician at the coroner's office died suddenly of suspicious causes.

In addition, at the Conservative Political Action Conference in Washington, D.C., just three weeks before Breitbart's death – where he promised to unveil "damning" new video evidence of Barack Obama's radical past that would change the election – Breitbart gave WND details of his upcoming revelations.

He claimed to WND that he had a video showing radical Weather Underground terrorist Bill Ayers and Barack Obama at Harvard planning revolution in the United States. But the video, aired just after he died, was of Obama introducing a radical Harvard professor, and the general response was flat.

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Filmmaker Steve Bannon, appointed executive chairman of the Breitbart News Network after Breitbart's death, has insisted to WND that the media mogul died of natural causes and to suggest anything else is irresponsible.

"Breitbart had an enlarged heart," Bannon told WND. "He had been hospitalized for the problem last year and told to lose weight that he did not lose."

Bannon, formerly a Breitbart News Network board member, told WND that for months prior to his death, Breitbart had been working overtime to finalize a refinancing of his news agency.

"He died of natural causes," Bannon said. "The family wants the matter put to rest, and WND is beginning to irritate me suspecting foul play."

In addition to Bannon, Laurence Solov, formerly president and chief operating officer, was elevated after Breitbart's death. Solov took Breitbart's place as CEO.

An eyewitness disappears

After recruiting the assistance of private investigators, WND found that Lasseter, the 26-year-old witness who saw Breitbart drop dead, is no longer residing at his last known address in California.

At the request of WND, Ohio-based private investigator Susan Daniels recruited a California-based private investigator to find Lasseter. The local investigator tried without success to find a cell phone or landline phone number for Lasseter.

After determining that Lasseter lived with his parents, Thornton, age 64, and Elaine, age 56, at a Los Angeles address, the investigator visited the residence in-person to see if he could make contact.

During the visit, the investigator reported, no one picked up the phone when he dialed the Lasseter apartment number outside the building. But he was greeted by a voice recording that identified different people at the apartment by first name, with none of the names on the recording being Christopher, Thornton or Elaine.

The investigator concluded Christopher Lasseter had "hunkered down" in what seemed to be an attempt to avoid further questioning.

He was unsure Lasseter was still residing at the address and considered it possible that Lasseter had moved.

On March 2, Crime File News reported Lasseter was walking his dog in Brentwood, Calif., when he saw Breitbart cross the street from the Brentwood Restaurant.

Breitbart was walking without apparent distress when he stepped on the curb "and fell like a sack of potatoes," Lasseter said.

He noted that Breitbart's skin color was bright red, which is not typically associated with heart attack victims.

Paul Huebl, who writes for Crime File News, reported April 22 that he interviewed Lasseter and added the detail that the witness was disturbed by Breitbart's color.

As a former Army medic, Huebl knew that most heart attack victims turned blue.

Coroner's assistant dies

On April 20, Los Angeles County Chief Coroner Craig Harvey released the autopsy report on Breitbart, listing the cause of death as heart failure resulting from an enlarged heart and some heart disease.

Harvey noted no prescription or illegal drugs were detected and only a small amount of alcohol was found in Breitbart's system at the time of death.

While the coroner concluded no foul play was suspected, his report made no attempt to explain why Lasseter observed Breitbart's skin was "bright red" at time of his death.

Then, within hours of the release of Breitbart's preliminary autopsy report, Michael Cormier, age 61, a forensic technician who worked as a photographer in the Los Angeles County coroner's office, died suddenly from what is suspected to be arsenic poisoning.

"At this point we haven't ruled out foul play," Los Angeles Police Lt. Alan Hamilton told the Los Angeles Times, referring to Cormier's sudden death. "It's one of the thing being considered. We are waiting for the coroner's results."

A video about Derrick Bell airs

At CPAC Feb. 10, Breitbart told the influential audience of grass-roots supporters that he planned to do the vetting on Barack Obama that the mainstream media failed to do in 2008. He promised to begin releasing videos within a few weeks.

"The videos are going to come out; the narrative is going to come out that Barack Obama met a bunch of silver ponytails back in the 1980s like Bill (Ayers) and Bernardine Dohrn, equally radical, who said one day we're going to have the presidency."

Breitbart told WND at CPAC that the not-yet released videos included footage of Ayers and Obama openly discussing revolution while Obama was a student at Harvard Law School.

The video released by Breitbart.com after Breitbart's death, however, showed law student Obama embracing Prof. Derrick Bell, a radical academic with ties to Rev. Jeremiah Wright, Obama's radical pastor for 20 years in Chicago.

"The video did not seem as earthshattering as Breitbart initially claimed it to be, just weeks before the 43-year-old unexpectedly passed away at his home last Thursday," the New York Daily News observed.

Bannon insisted to WND that the video released by Breitbart.com after Breitbart's death was the film Breitbart referred to when speaking in February to CPAC.

"There is no other footage," Bannon insisted. "We were working on the Derrick Bell video when Breitbart died, and we released to the public the video we have."

However, in a contentious March 8 interview with CNN's Soledad O'Brien, Breitbart.com Editor in Chief Joel Pollack said the Bell video was just "one of the materials Andrew Breitbart was talking about."

It was "not his final bombshell," Pollack said.

"This is the beginning of a vetting process that begins with Andrew Breitbart's probe into Barack Obama's time in Chicago and will continue," he explained.

On Feb. 5, Breitbart had dinner cooked by Ayers at the home of Ayers and Dohrn after Daily Caller publisher Tucker Carlson won a "Super Bowl Dinner" auctioned off by Ayers for $2,500.