A bail hearing was expected Friday for the U.S. citizen arrested this week along with four other men as part of an ongoing probe into alleged terrorism in northern California.

Law enforcement sources are saying they expect some of the men named in an affidavit released earlier this week to be indicted by a grand jury in the next several weeks. Terror charges are expected to be filed against some of the individuals.

The scope of the alleged conspiracy is still under investigation but sources say the probe is in high gear and authorities have been following new leads, interviewing more people and conducting new surveillance. The probe has spread to leads that are being investigated in Sacramento and San Francisco.

Hamid Hayat (search), 22, is accused of training with Al Qaeda (search) in Pakistan and planning to attack hospitals and supermarkets in the United States. He is scheduled to appear in federal court Friday for a bail hearing.

Umer Hayat, 47, said his son was drawn to jihadist training camps in his early teenage years while attending a madrassah, or religious school, in Rawalpindi, Pakistan, that was operated by Umer Hayat's father-in-law, according to an FBI affidavit.

Hayat allegedly paid for his son to attend the terrorist camp in 2003 and 2004. The affidavit says it was run by a friend of his father-in-law's.

The Hayats are charged only with lying to federal investigators.

Click here to view the criminal complaint (FindLaw).

Two Islamic religious leaders, or imams, and one leader's son also have been detained on immigration violations. Neither FBI spokesman John Cauthen nor a spokeswoman for U.S. Immigration and Customs Enforcement would reveal specifics of the alleged visa violations.

Saad Ahmad, an attorney for the three men, did not immediately return a telephone call Thursday seeking comment.

Federal authorities aren't saying much about their terrorism investigation but are making two things crystal clear: Their work in the farming town has been going on for years — and it's not over yet.

They denied the implication by some members of Lodi's large Pakistani community that the probe was triggered by a rift between fundamentalist and mainstream factions.

Each side accused the other of contacting the FBI, which is in charge of the investigation. The dispute has led to a leadership struggle at the Lodi Muslim Mosque and a legal fight with a budding Islamic learning center.

The FBI alleges several people committed to Al Qaeda have been operating in and around the rural community 40 miles south of Sacramento.

Community leaders spoke to FOX Friday morning about the investigation. Lodi Mayor John Beckman said the community was still surprised over the arrests but was doing its best to cooperate with federal authorities. He said city police were allowing the FBI to conduct interrogations at facilities in the city instead of in Sacramento.

"A lot of [Muslims in the community] are concerned about their safety and the way the FBI is conducting the investigation," Beckman told FOX.

Beckman defended the city's vigilance in the fight against terrorism and said the city's responsibility was not to fight international terrorism, but to the safety of its citizens.

Larry Hansen, a city council member, also defended Lodi's authorities. "No terrorist activity has been going on in Lodi," Hansen told FOX.

"There's about 2,300 members of the Muslim community that live in Lodi and a lot of them are very concerned about the residual effects of this type of publicity," Hansen said.

The sequence that led to the arrests and detentions began May 29, when Hamid Hayat was trying to return to the U.S. but was identified in mid-flight as being on the federal "no-fly" list. His plane was diverted to Japan, where Hayat was interviewed by the FBI and denied any connection to terrorism.

He was allowed to fly to California, but was interviewed again last weekend. He and his father were charged after he flunked a lie detector test and then admitted attending the training camp, the affidavit said.

The Hayats and the imams are on opposite sides of a struggle between Pakistani factions in and around Lodi: The Hayats are aligned with a faction supporting more traditional Islamic values; the imams with another group seeking greater cooperation and understanding from the larger community.

Adil Khan was trying to start an Islamic center but has been sued by the Lodi Muslim Mosque, which claims he improperly transferred mosque property.

"It may well be that some of this is gamesmanship," said attorney Gary Nelson, who represents Khan in the civil lawsuit. "But we are talking about the FBI and INS, and they don't do this lightly. At least I hope they don't."

Lawyers for the Hayats are questioning why the FBI changed the affidavit. They maintain that copies released in Washington and Sacramento are significantly different.

The Washington version, released first, said Hamid Hayat chose to carry out his "jihadi mission" in the United States and potential targets included "hospitals and large food stores." The reference to the targets was dropped in a later version filed in federal court in Sacramento.

Hamid Hayat's attorney, Wazhma Mojaddidi, said that revision "strikes us as an odd turnabout."

Umer Hayat's attorney, Johnny Griffin III, said he was irritated that the government made public the references to hospitals and supermarkets, and then filed something different with the court.

Cauthen described the changes as routine revisions. Authorities said they had no indication of specific plans or timetables for an attack.

"There is no specific information about hospitals and food stores," he said. "They didn't stand out above other sectors of the infrastructure."

Other law enforcement sources said the initial draft was mistakenly passed out to media outlets, despite concerns it would cause media focus and panic.

FOX News' Catherine Herridge and Anna Persky and The Associated Press contributed to this report.