FBI terrorism experts are investigating whether the death of a Somali-born Canadian citizen — whose body was found Monday in a Denver hotel room with about a pound of extremely toxic sodium cyanide — is connected to the upcoming Democratic National Convention.

The Denver coroner said the man died of cyanide poisoning.

The cause of death was announced Thursday, but authorities haven't determined whether 29-year-old Saleman Abdirahman Dirie committed suicide.

An FBI Joint Terrorism Task Force has been sent to Denver, although Special Agent Kathy Wright said there's no information to conclude that Dirie had terrorist ties, the Rocky Mountain News reported.

While local law enforcement officials tried to downplay the incident, stressing that there was no sign of foul play in the death of Dirie, a Defense Department contractor said it's likely a terror plot could have been in the works, considering the toxicity and reported amount of cyanide found with the 29-year-old from Ottawa.

"I don't see how anybody could do anything but look into the possibility that this is a potential terrorist attack," Dr. Andrew Ternay told CBS 4 News in Denver.

The FBI, however, said Wednesday that there's probably no reason for them to go back to the fourth-floor room at the Burnsley Hotel, where Dirie was found.

The hotel is located about four blocks from the Denver state Capitol.

"It's an isolated incident," Denver Police Detective John White told the newspaper. They refused to speculate on why he had such a large quantity of the poisonous substance with him in the swanky all-suite hotel so soon before the convention in Denver, Aug. 25-28.

"We don't think it's any act of terrorism," Sonny Jackson, a spokesman for the Denver Police Department, told FOXNews.com. "We have no reason to believe it was. Nobody knows what was in this gentleman's mind."

Jackson declined to elaborate on why the FBI's Joint Terrorism Task Force got involved in the case.

"That's just normal," said Jackson. "You'd have to ask them why they got involved. They may have more expertise with the chemicals."

Sodium cyanide is commercially available and commonly found in rat poison and used to extract fold and other precious metals. When inhaled or ingested, the chemical prevents the body from processing oxygen. It can also be mixed with certain acids to produce extremely lethal cyanide gas, according to the Department of Justice.

In July, a person calling himself "Abdirahman Dirie" posted an online comment with a blog that discussed the killing of Christians by Islamic Courts and Islamists in Somalia. It was not known whether it was the same person as the Dirie found dead in Denver.

"Please on't [sic] talk sh—t, that man [the Christian blogger] deserves what happened to him, simply because having the bible in one hand, and a bread in the other hand, is not a correct thing,! Kill Them, Kill them, Kill them, that is my massage [sic],!" — comment by Abdirahman Dirie, July 11, 2008 @10:33 p.m.

But the FBI echoed police, insisting terrorism isn't suspected.

"At this point we don't have any nexus to terrorism," the FBI's Wright told The Associated Press. She didn't immediately return a phone call seeking comment from FOXNews.com.

Dirie's sister, meanwhile, is upset over the implication that her brother might have been planning some sort of massive deadly attack.

"He was not a terrorist," his sister, who declined to give her name, told the Montreal Gazette. "We don't want to hear that word, it hurts us. It is against our religion."

She told the Gazette that he was diagnosed with schizophrenia about three years ago and was taking medication.

She said her brother was "fine" and wasn't suicidal. Police said they were investigating whether Dirie took his own life.

"That's a possibility," Jackson told FOXNews.com. "I'm not going to speculate. It's just a death investigation at this point."

Fire officials said they found a bottle of the white powder in Dirie's room, about a quart by volume, that was confirmed by police Wednesday to be cyanide.

Jackson declined to confirm how much was found.

"We aren't releasing any amount," he told FOXNews.com. "We don't even know how much. It's basically readily available for commercial use."

Investigators have not said why Dirie had cyanide or whether he worked in a job that would have involved using it. They also have not said how long Dirie had been in Denver or whether anyone had accompanied him, though he didn't appear to have ties to the city.

The State Department said privacy laws prevented the release of any information about the type of visa Dirie may have had.

The Canadian Consulate in Denver said members of Dirie's family were in Colorado to make arrangements to return his body to Canada.

Addirizuk Karod, manager of Ottawa's Somali Centre for Family Services, told the Ottawa Sun that Dirie was a member of the city's Somali community and had been to the center with friends.

Karod told the newspaper the Dirie family had left Somalia as refugees years ago and had become Canadian citizens.

Hotel general manager Jason Ford declined to offer specific information about Dirie. He said other guests have been moved from the fourth floor, where Dirie's room was, to avoid inconvenience from the investigation.

An advocacy group for Somali immigrants cautioned against linking Dirie to terrorism.

The Somali Justice Advocacy Center in St. Paul, Minn., said Thursday that connecting Dirie's death to terrorism "is a rush to judgment."

Click here for more on this story from ABC 7 News in Denver.

Click here for more on this story from the Denver Post.

Click here for more on this story from the Montreal Gazette.

Click here for more on this story from CBS 4 News in Denver.

FOXNews.com's Catherine Donaldson-Evans and The Associated Press contributed to this report.