A Pakistani man who was arrested earlier this year for allegedly plotting to assassinate current and former U.S. government officials now faces accusations of terrorism, according to an indictment filed in federal court on Tuesday.

Asif Merchant was initially charged in July on a single count of murder for hire in a criminal complaint that alleged he flew to the U.S. to "recruit individuals to carry out his plot to assassinate U.S. government officials." A new two-count indictment unsealed Tuesday in the U.S. District Court for the Eastern District of New York reiterated the murder-for-hire count and added a charge accusing Merchant of attempting to carry out an act of terrorism.

The 46-year-old with alleged ties to Iran "attempt[ed] to kill a person within the United States" who was either "a member of the uniformed services" or "any official" of the U.S. government, the indictment said in describing the new charge.

Neither the original complaint nor the new indictment named Merchant's alleged targets. Investigators alleged he planned to tell his co-conspirators who he was going to attack later in the summer. But multiple sources familiar with the investigation told CBS News last month Merchant planned to assassinate current and former government officials across the political spectrum. Merchant had yet to finalize the plan, but former President Donald Trump was among the possible targets, the people said.

GOP Sen. Chuck Grassley of Iowa said last week that evidence his office received detailed information that President Biden and former U.N. Ambassador Nikki Haley were also potential targets.

Details about Merchant's alleged ties to Iran remain scarce. Charging documents filed earlier this year said he had "a wife and children in Iran" and records "indicated frequent travel to Iran, Syria, and Iraq." He traveled to Iran in April 2024, the complaint alleged, before traveling to the U.S.

Investigators said he then met with an unnamed co-conspirator-turned-FBI-informant in New York. The two began a months-long relationship, with Merchant eventually revealing his plans, charging documents said.

Merchant allegedly sketched out the plot on a napkin inside his New York hotel room, prosecutors said, and told the individual "that there would be 'security all around' the person" they were planning to kill.

The unnamed individual arranged to have Merchant meet up with two undercover agents who Merchant thought were hitmen. "During the meeting, Merchant presented himself as the 'representative' in the U.S., indicating that there were other people he worked for outside the U.S.," prosecutors wrote.

According to the criminal complaint, Merchant told the men he would provide more instructions about the alleged plot in "either the last week of August 2024 or the first week of September 2024," including the target's name.

Federal officials arrested him in July before a planned trip abroad. During a search, investigators said they found a handwritten note that contained the codewords for the various aspects of the plot.

Merchant has remained in custody and pleaded not guilty to the original single-count complaint. He has not yet been arraigned on the updated charge. His attorney did not immediately respond to a request for comment.

Intelligence about Merchant's alleged plot featured prominently in the information that prompted the U.S. Secret Service to increase security assets for the former president in recent months, sources familiar with the probe told CBS News. Merchant was arrested one day before the July 13 assassination attempt against Trump in Pennsylvania, but officials have said there is no indication that his alleged plan of attack was related to that shooting.

"Law enforcement foiled the charged plot before any attack could be carried out. Our ongoing investigation has not found evidence that this defendant (Merchant) had any connection to the shooting in Butler, Pennsylvania," a law enforcement official said last month in a statement to CBS News.

U.S. intelligence and law enforcement officials including FBI Director Christopher Wray have been investigating numerous threats from Iran against politicians and government officials that date back to the killing of top Iranian Gen. Qassem Soleimani during the Trump administration.

"The Justice Department will not tolerate Iran's efforts to target our country's public officials and endanger our national security," Attorney General Merrick Garland said in a statement Wednesday.