Federal authorities are expected to announce charges against eight more people today in a long-running investigation into how perhaps dozens of young men from the Minneapolis area were recruited to join an Al Qaeda-linked group in Somalia.

It will be the most significant and public move to date in the case. Although indictments against six people had already been unsealed, the question of who helped persuade more the men to train and fight with the group has remained largely unanswered.

Among the charges being announced today: solicitation to commit a crime of violence.

The charges will be announced at a joint FBI-U.S. Attorney’s Office press conference in Minneapolis on Monday afternoon, a source said.

According to court documents, at least six people – Zakaria Maruf, Mohamed Abdullahi Hassan, Mustafa Ali Salat, Ahmed Ali Omar and Khalid Mohamud Abshir — have been indicted on several counts, including conspiracy to provide material support to terrorists, and providing material support to a foreign terrorist organization.

Omar and Abshir are also charged with solicitation to commit a crime of violence, charges not yet seen in the FBI’s case.

Many of those charged have already been arrested, but some individuals are currently overseas, the source said. The source did not elaborate.

Beginning in late 2007 and continuing through last year, more than 20 young men left their homes in the Minneapolis area to join al-Shabaab, which is fighting to establish a Muslim state in Somalia and recently pledged its allegiance to Usama bin Laden.

U.S. officials worry that if al-Shabaab prevails, Somalia could turn into a haven for Al Qaeda and other terrorist groups.

After families in Minneapolis began to report their sons missing, the FBI launched a wide-ranging investigation.

By March federal authorities were aware that several Minnesota men who traveled to Somalia had returned to the United States, but they were not arrested immediately so that federal authorities could continue their investigation, a law enforcement source said.

One of the Minneapolis area’s most popular mosques, the Abubakar As-Saddique Islamic Center in St. Paul, has become a point of interest for investigators and a subject of speculation among those watching the case.

Many of the men recruited to join al-Shabaab attended the Abubakar mosque, and some of the latest individuals to be charged have ties to the mosque, a source said.

“But don’t look for that to be at the center of the announcement,” the source said. The source said no mosque officials will be part of Monday’s announcement.

A call to the mosque was answered by a machine, and efforts to reach the mosque’s director were not successful.

In March, the mosque posted a statement online saying any suggestions it played a role in recruitment of young men to Somalia were untrue and “unfair.”

“Abubakar Center didn’t recruit, finance, or otherwise facilitate in any way, shape, or form the travel of those youth,” the statement said.

Authorities have so far remained mostly quiet about the progress of their investigation, as indictments related to the case were sporadically being unsealed.

In July, FOX News first reported that a federal grand jury in Minneapolis had indicted three Somali-American men in the case. Two have since pleaded guilty to providing material support to terrorists, and one has admitted that he lied to investigators.

More recently, another man was indicted for lying to FBI agents, but he has pleaded not guilty.

Two weeks ago, a Somali man was arrested in the Netherlands for allegedly financing terrorist activities. U.S. authorities are working with Dutch authorities to extradite him to the United States, a source said.

Last week one more Minnesota man was indicted on charges of conspiracy to provide material support to terrorists. He is scheduled to be arraigned Tuesday.

Somalia has had no stable government since 1991, when dictator Siad Barre was ousted from power. A newer secular government has had trouble keeping Muslim militants at bay, and in 2006 fighting with al-Shabaab intensified after Western-backed Ethiopian forces invaded Somalia.

The U.S. government labeled al-Shabaab a terrorist organization last year.

In October 2008, 27-year-old college student Shirwa Ahmed of Minneapolis became “the first known American suicide bomber” when he blew himself up in Somalia, killing dozens, according to the FBI. Since then at least four more men from Minneapolis have been killed in Somalia, according to their families.