(CBS NEWS) The widow of Omar Mateen, the shooter in the Orlando nightclub massacre, has been arrested in San Francisco, sources tell CBS News.

Noor Salman is facing charges of aiding and abetting, as well as obstruction of justice in the case of the worst mass shooting in American history. She moved to the San Francisco area after the June shooting, in which her husband was killed by SWAT team members after slaughtering 49 people inside a popular gay nightclub.

Salman is expected to make her first appearance tomorrow in San Francisco.  

Mateen pledged allegiance to the Islamic State of Iraq and Syria (ISIS) during a three-hour standoff. Salman has told the FBI that her husband had become radicalized in the year before the attack. 

During the shooting, Mateen was communicating with Salman via text message. A law enforcement source said the couple exchanged, “I love you.”  

Law enforcement sources have long suspected she had a role in the attack, saying previously that Salman purchased ammunition with her husband, and they believe she drove with him as he cased the Pulse nightclub prior to the shooting.  

CBS News senior investigative producer Pat Milton reportd Salman was interviewed multiple times by the FBI and was administered a polygraph test.

She told FBI investigators she tried to stop her husband from committing the attack.

However, as CBS News correspondent Jeff Pegues has reported, officials were concerned that she had knowledge of the attack but never reached out to law enforcement in an attempt to prevent it. 

The FBI is characterizing the shooting at Pulse nightclub as both a terrorist attack and a hate crime.

Last month, Salman petitioned to have the name the son she had with Mateen changed. An online docket from Contra Costa County, California, shows that Salman filed the petition in December on behalf of the 4-year-old boy, who is partly named for his father. A hearing is scheduled for February.

This is a developing story. Please check back in frequently for updates.