Commissioner Thomas Braidwood said he was appalled by the revelations in the email on Friday. (CBC)

The unexpected disclosure of a key email between senior RCMP officers has raised questions about officers' testimony at the Braidwood inquiry into the death of Robert Dziekanski, resulting in a delay of the probe in Vancouver until September.

The email between two senior RCMP supervisors suggests that the four Mounties who responded to a call at the airport discussed a plan to use a Taser against the Polish immigrant before they arrived.

The four officers had already stated under oath at the inquiry that they had not discussed using the stun gun before arriving at the airport.

The commission was scheduled to begin hearing closing arguments on Friday morning, but after learning of the email, commissioner Thomas Braidwood announced the inquiry will resume on Sept. 22, so the commission lawyers have time to review the email and conduct an investigation.

"I am obviously appalled," a clearly upset Braidwood said.

'Discussed the response en route:' email

The existence of the email was revealed by commission counsel Art Vertlieb as the inquiry resumed Friday. He said he only received the email from federal lawyers on Tuesday.

Commission counsel Art Vertlieb said he only learned of the email on Tuesday. (CBC)

Vertlieb read from the Nov. 5, 2007, email, titled "Media strategy — release of the YVR video,'" from the RCMP Chief Supt. Dick Bent to assistant commissioner Al McIntyre.

"Finally, spoke to Wayne and he indicated that the members did not articulate that they saw the symptoms of excited delirium, but instead had discussed the response en route and decided that if he did not comply that they would go to CEW."

The "Wayne" mentioned in the email is Supt. Wayne Rideout, then-head of the Integrated Homicide Investigation Team investigating Dziekanski's death, according to Vertlieb. CEW refers to a conducted energy weapon, the RCMP name for a Taser-type weapon.

Vertlieb said the late disclosure throws into question whether the commissioner has received everything he needs from the RCMP, and argued that the closing submissions should be delayed so the RCMP officers involved can be called to testify about the email and a full review of the disclosure process can be completed.

Vertlieb acknowledged the comments on the email were clearly hearsay, but that they must be investigated because they came from senior RCMP officers, and "on its face, the email appears to tell a significantly different story."

Wrong and hearsay: officers' lawyers

Lawyers, representing the four RCMP officers who were at the airport, responded that the email was essentially wrong and hearsay, and reiterated the officers' statement that they had not discussed using the Taser prior to arriving.

Federal government lawyer Helen Roberts gave a tearful apology for the failure to disclose the documents. (CBC)

"It never happened," Ravi Hira, the lawyer for Const. Kwesi Millington, later told CBC News.

"What possible reason would there be to have such a plan," said Hira, "the evidence doesn't support this fanciful tangent that we are going down at the public expense."

But Braidwood ruled the inquiry will resume on Sept. 22, when it's likely Rideout, Bent and McIntyre and other RCMP officers would be required to testify about the email.

The email was apparently overlooked by federal government lawyers in the thousands of pages of documents received from the RCMP on CD-ROMs during the inquiry.

A clearly upset Vertlieb berated the federal lawyers for the mistake, saying: "This is what late disclosure does — it disrupts the conduct of the proceedings."

Helen Roberts, a lawyer for the federal government, gave a tearful apology, saying it was simply an accidental oversight.