DENVER -- An Afghanistan-born Colorado man, his father and a New York City imam are expected to make initial court appearances on Monday on charges of lying to federal authorities in a terrorism probe.

Najibullah Zazi, 24, a Colorado airport shuttle driver who has admitted receiving weapons training from al-Qaida, played a direct role in an alleged terror plot, according to court documents released Sunday. Authorities have said they don't know the timing or location of any planned attack.

Investigators said they found notes on bomb-making in Zazi's handwriting and that they discovered his fingerprints on materials -- batteries and a scale -- that could be used to make explosives.

Zazi and his 53-year-old father, Mohammed Wali Zazi, were arrested Saturday in Denver. Ahmad Wais Afzali, 37, was arrested in New York, where he is an imam at a mosque in Queens.

The three are accused of making false statements to the government. The Zazis were scheduled to appear in federal court in Denver on Monday, the Justice Department said. Afzali was to appear Monday in federal court in New York.

If convicted, they face eight years in prison.

ABC News reported Sunday that federal investigators are looking at the possibility eight more people may be involved in the ongoing terror investigation centering on Aurora and New York City.

ABC's Chief Investigative Correspondent, Brian Ross, told 7News the eight could be part of the same cell, but operating in two different areas.

Ross said Zazi is believed to be one of just two people who may know the players on both sides of the cell. The other person is a man believed to have accompanied Zazi to Pakistan in 2008. Ross said investigators are concentrating their search for him in Colorado.

Zazi has repeatedly denied to reporters any connection to al-Qaida or to a purported terrorist plot.

A senior U.S. intelligence official in Washington told The Associated Press Friday that Zazi has indicated that he is directly linked with al-Qaida. The official, who spoke on condition of anonymity in order to discuss intelligence matters, said Zazi played a crucial role in an intended terrorist attack but that it was not immediately clear what the targets were.

The FBI is investigating several individuals in the United States, Pakistan and elsewhere in an alleged plot to detonate explosive devices in the United States, the Justice Department said in a statement.

"The arrests carried out tonight are part of an ongoing and fast-paced investigation," said David Kris, assistant attorney general for national security. "It is important to note that we have no specific information regarding the timing, location or target of any planned attack."

A joint FBI-New York Police Department task force feared Zazi may have been involved in a potential plot involving hydrogen peroxide-based explosives like those cited in an intelligence warning issued Monday, according to two other law enforcement officials, who spoke on condition of anonymity because they were not authorized to speak about the investigation. Zazi denies any ties to al-Qaida or terrorism.

At a celebration for the end of Ramadan that drew an estimated 5,000 people to a hotel in suburban Aurora Sunday morning, there was suspicion and concern over the arrest.

Taj Ashaheed, Colorado Muslim Society spokesman, said he was surprised that the three men were only charged with lying to authorities, considering the hype that has surrounded them.

"No one here subscribes to the idea of terrorism. We're citizens, too," he said. "If these things are true, it's disturbing and troubling, particularly to the Muslim community."

In supporting documents filed with the court, investigators say Zazi admitted to FBI agents last week that in 2008 he received weapons and explosives training from al-Qaida in the federally administered tribal areas of Pakistan.

The terror probe gathered momentum after Zazi rented a car and drove from Denver to New York, crossing into Manhattan on Sept. 10. Zazi said he went to New York to resolve some issues with a coffee cart he owns in Manhattan, then flew home to Denver. The FBI searched Zazi's rental car and laptop during the New York trip and listened in on telephone conversations, according to the affidavits.

On Monday, FBI agents and police officers with search warrants seeking bomb materials searched three apartments and questioned residents in the Queens neighborhood where Zazi stayed.

A Sept. 11 search of Zazi's rental car in New York turned up a laptop computer that contained an image of nine pages of handwritten notes, according to court documents filed with the arrest warrant. Those notes included instructions about how to build explosives and detonators, the affidavits state.

Zazi was asked about the notes during FBI interviews last week and said he knew nothing about them, the documents said. Zazi allegedly told federal agents that he must have unintentionally downloaded the notes along with a religious book. He said he deleted it within a few days after realizing it discussed jihad, the affidavit said.

However, federal agents suspect Zazi received the notes via e-mail.

Authorities have found images of the notes in two e-mail accounts with similar passwords. One of the accounts has a nine-digit password that is identical to the password for an e-mail account that Zazi told investigators this week was his, the affidavit said.

Authorities suspect Zazi controls both e-mail accounts that received copies of the handwritten notes, according to the affidavit.

An arrest warrant affidavit says FBI agents intercepted a phone conversation around Sept. 11 in which Afzali, a legal permanent resident from Afghanistan, told Zazi that he had spoken with authorities. "I was exposed to something yesterday from the authorities. And they came to ask me about your characters. They asked me about you guys," Afzali told Zazi, according to the affidavit.

However, Afzali allegedly lied to authorities about that conversation when federal agents asked him about it Thursday, according to the affidavit.

The department says Mohammed Zazi, a naturalized U.S. citizen who was interviewed last week by the FBI, lied when asked if he knew anyone by the name of Afzali and said he didn't. The FBI said it had wiretapped a conversation between Mohammed Zazi and Afzali during Najibullah Zazi's visit to New York.

Wendy Aiello, a spokeswoman for Zazi's defense team, says Zazi and his father were taken to FBI headquarters in Denver.

Zazi had been scheduled to go to the Federal Building in Denver on Saturday for a fourth straight day of FBI questioning. However, the meeting was canceled so Zazi could meet with his attorney, Aiello said.

The FBI searched Zazi's apartment and his uncle and aunt's home last week in suburban Denver. Authorities have not said what they found.

Meanwhile, Colorado's Muslim community is concerned that the new information will lead to a backlash against areas Muslims.

"After 9-11, there were some issues, but we put that behind us," said Ziyad Sarsour, president of the Colorado Muslim Society. "We just hope that it doesn't reappear... Just like any other community you'll find one or two people who aren't good, but 99.9 percent of Muslims are peace-loving people."

Zazi was born in Afghanistan in 1985, moved to Pakistan at age 7 and emigrated to the United States in 1999. He returned to Pakistan in 2007 and 2008 to visit his wife, according to his attorney, Arthur Folsom.