An FBI agent at a scene of investigation. (AP/David Goldman)

Self-described American jihadist Mahin Khan faces a three-count indictment, including terrorism, conspiracy to commit terrorism and conspiracy to commit misconduct involving weapons.

A Tucson man has been arrested by the FBI and the Arizona Attorney General’s Office for threatening to commit acts of terrorism on Arizona government buildings and against “Marines and Jews.”

The Attorney General’s Office says 18-year-old Mahin Khan appeared before a Phoenix judge last Saturday morning.

He was ordered held without bond in Maricopa County Jail.

Khan faces a three-count indictment, including terrorism, conspiracy to commit terrorism and conspiracy to commit misconduct involving weapons.

Arizona Attorney General spokeswoman Mia Garcia says Khan is accused of conspiring to carry out terrorism acts on government buildings in Phoenix and Tucson.

Garcia declined to give further details, saying Khan’s court records are currently sealed.

Mahin Khan

Suspected ISIS supporter Mahin Khan. (Maricopa County Sheriff’s Office via AP)

The FBI investigation began with citizens alerting authorities to suspicious behavior.

On Thursday, a grand jury has indicted the accused Islamic State (ISIS) sympathizer on charges of plotting to stage an attack on Phoenix-area Jews and other targets with bombs and other weapons.

He faces a maximum penalty of life in prison if convicted with aggravating factors proven at trial, Garcia said.

Khan reportedly sought to “obtain weapons including pipe bombs or pressure cooker bombs” for an attack on a Motor Vehicle Division office in Maricopa County.

In a probable cause statement filed in the case earlier this week, the FBI said Khan described himself in an email as an “American Jihadist who supports” ISIS.

In an email, Khan asked a contact he believes to be Pakistani to provide him with assault rifles and a pistol because he wanted to “take out marines and Jews.”

Speaking in June, FBI Director James Comey said that ISIS  is currently the main threat facing the United States, both in its efforts to recruit fighters to join it in Syria and Iraq and to have others carry out violent attacks on American soil.

He said the FBI is continuing to focus on ISIS, and there are close to 1,000 open cases nationwide involving people at various stages of recruitment.

By: AP and United with Israel Staff