UPDATE | Brother, others related to San Bernardino shooters arrested

LOS ANGELES (AP) — The brother of one of the San Bernardino shooters was arrested with two other family members today in Southern California in what prosecutors say was a marriage scheme to fraudulently allow one of them to remain in the United States.

Prosecutors say they uncovered the sham marriage during the investigation into the Dec. 2 shootings that killed 14 and wounded 22 others. The gunmen – Syed Rizwan Farook and his wife, Tashfeen Malik – died in a shootout with police.

Authorities arrested Farook's brother and sister-in-law, and the wife of Enrique Marquez Jr., Farook's longtime friend, in the marriage fraud case. The two women are sisters and Russian immigrants, and came to the U.S. on visas for work or student exchanges.

The sham marriage was between Marquez and Mariya Chernykh, prosecutors said. They wed so she could obtain immigration benefits unavailable to her as a Russian citizen without legal status in the U.S., according to authorities.

The FBI has said Marquez acknowledged getting $200 a month to marry Chernykh, and bank statements back that up, according to the indictment charging the trio.

None of the three is accused of involvement in the attack, though Marquez has been charged with conspiring with Farook to provide material support to terrorists.