WASHINGTON

- The U.S. government appears not to have picked up on extremist messages exchanged during the online courtship two years ago between the American-born man accused in the California shootings and his then-fiancée in Pakistan, according to information provided by federal officials in a closed-door briefing to Congress yesterday.

American officials say Syed Rizwan Farook and his wife, Tashfeen Malik, discussed martyrdom and jihad online as early as 2013. But the couple never surfaced on law- enforcement's radar and Malik was able to enter the U.S. on a fiancée visa last year despite having professed radical views online.

Meanwhile, the investigation into the shootings that left 14 dead last week continued in San Bernardino, where an FBI dive team searched a small, urban lake about 3 miles north of the shooting site.

David Bowdich, chief of the FBI's Los Angeles office, said investigative leads indicated the shooters had been in the area the day of the massacre and said the search of the lake could take days. He declined to discuss what time of day the leads indicated they may have been there. He also declined to specify what the divers were looking for.

FBI Director James Comey and other senior American officials briefed members of Congress, who are curious to know if any red flags were missed in the last two years.

New revelations also show a much deeper connection between Farook and Enrique Marquez, his friend who bought the assault rifles used in the shooting, than previously was disclosed. Marquez has not been charged.