A U.S. citizen on the FBI’s Most Wanted Terrorist List has been charged with additional crimes involving ties to Somalia’s al-Shabaab rebel group, according to a federal indictment unsealed Monday.

Jehad Serwan Mostafa, 37, a former San Diego resident, was indicted on similar charges in 2009.

Without providing specifics, the new counts accuse him of having key roles in al-Shabaab activities and providing material support from 2008 to 2017.

The FBI did say it learned this year that he is a leader in al-Shabaab’s “explosives department.”

“Today, Mostafa is believed to be the highest-ranking United States citizen fighting overseas for a terrorist organization,” said Scott Brunner, the agent in charge of the FBI office in San Diego.

The group claimed responsibility for two Sept. 30 attacks on U.S. and European military targets in Somalia, including one by an estimated 25 fighters who were killed when they tried to storm the Belidogle military airstrip, which hosts Somali and U.S. forces.

Mostafa was born in Wisconsin, raised in the Serra Mesa area in San Diego and later attended San Diego Mesa College. He went on to attend the University of California, San Diego, where he graduated in 2004 and joined al-Shabaab around 2006, according to FBI Special Agent in Charge Scott Brunner.

Mostafa was among a handful of young Muslims from the U.S. who took high-visibility roles inside the al-Qaida-linked insurgent force.

He was once president of the now-defunct Muslim Youth Council of San Diego, which said on its website that it was “dedicated to showing the world that Islam is a religion of peace and Muslims are a peaceful and productive part of society.”

Mostafa's father, Halim Mostafa, a Kurdish Syrian, made a low-budget film, “Mozlym,” that was released in 2008 and billed as an effort to show how the true meaning of Islam is often lost amid misconceptions of non-Muslims in America.

In August 2010, NBC 7 reported that Mostafa was a former employee at an auto shop located on El Cajon Boulevard.

Brewer said the actions of al-Shabaab have had a direct impact on the San Diego community.

“Specifically, the United States citizen working for a San Diego non-profit organization was killed in 2010 during an attack in Uganda during the world cup. And a Torrey Pines high school graduate was injured in 2013 during an al-Shabaab attack on the Westgate mall in Nairobi, Kenya.”

The FBI played videos during the press conference Monday from a 2011 event where Mostafa was seen paying homage to Osama bin Laden. He was described as an “Al-Qaeda representative.”

Mostafa is likely in southern Somalia, where the al-Shabaab stronghold is, the FBI said; however, the goal of Monday’s press conference was to ask the public’s help in narrowing down the government’s search.

The FBI is offering up to a $5 million award for information that can lead to the Mostafa’s arrest.

The government confirmed Mostafa has relatives in the San Diego area.