Last Updated Dec 11, 2015 6:30 PM EST
A friend of one of the San Bernardino attackers spoke about terrorism and sleeper cells at the Southern California bar where he worked, The New York Times reported Friday.
Enrique Marquez was a friend and and relative-through-marriage of Syed Farook, who with his wife, Tashfeen Malik, carried out last week's rampage at a holiday luncheon that killed 14 people. Marquez purchased the assault rifles that Farook and Malik used in the attack.
A senior law enforcement official told CBS News justice correspondent Jeff Pegues that investigators have examined Farook and Malik's cell phones and have found "levels of built-in encryption." The official said investigators did not know if the couple used the encryption to conceal conversations because technicians at the FBI lab have been unable to get into certain parts of the devices' memory.
In addition, investigators were still looking for connections between Farook, Malik and ISIS leadership which could demonstrate that the attack was directed by the terrorist organization. So far, investigators have only been able to determine that the San Bernardino attack was at least inspired by ISIS.
Nick Rodriguez, a customer at Morgan's Tavern in Riverside where Marquez worked, told the Times that the 24-year-old talked about terrorism when he was drinking.
"He would say stuff like: 'There's so much going on. There's so many sleeper cells, so many people just waiting. When it happens, it's going to be big. Watch,'" Rodriguez told the newspaper. "We took it as a joke. When you look at the kid and talk to him, no one would take him seriously about that."
Marquez, who checked himself into a mental hospital after the attack, told investigators that he and Farook were plotting an attack in 2012. The FBI is trying to corroborate that claim, CBS News has learned.
Idaho Sen. Jim Risch, a Republican who sits on the Senate Select Committee on Intelligence, said they had an actual plan, including buying weapons, but became apprehensive and shelved it because of law enforcement activity and arrests in the area. Marquez hasn't been charged with a crime.
Lawmakers said the FBI wouldn't provide details about his ties to the case, citing an "ongoing criminal investigation." Marquez's mother Armida Chacon told reporters Thursday that her 24-year-old son is a good person.
Meanwhile, an FBI dive team searched a small, urban lake about 3 miles north of the shooting site. CBS News has learned that the divers are looking for a computer hard drive that may have been dumped in the lake as well any other items Farook and Malik may have thrown in it.
On Friday, a diver was seen handing an item to investigators.
Authorities said the shooters had been in the area. The couple died in a shootout with law enforcement hours after the attack and left behind a 6-month-old daughter.
American officials said the couple discussed martyrdom and jihad online as early as 2013. But they never surfaced on law enforcement's radar and Malik was able to enter the U.S. on a fiancee visa last year despite having professed radical views online.
FBI Director James Comey and other senior American officials on Thursday briefed members of Congress, who were curious to know whether any red flags may have been missed in the last two years.
"Everyone's asking the same questions about how it is that law enforcement didn't know, or intelligence officials didn't know - that they could have flown under the radar and nothing gave an indication that they were a threat," said Rep. Jim Langevin, a Rhode island Democrat and member of the House Homeland Security Committee.
Rep. Adam Schiff, the top Democrat on the House Intelligence Committee, said it was his understanding that Malik was subjected to an in-person interview during the application process for a visa, but that he did not have additional details on it. He noted that while there were some indications that might have alerted law enforcement to Farook, he declined to detail what those might have been.
"I don't think we know yet enough to say these were apparent without the advantage of hindsight," Schiff said.
Republican Rep. Will Hurd of Texas, a member of the House Homeland Security Committee, said there's currently no evidence Malik's radicalization would have been readily apparent when she was evaluated for a fiancee visa.
"I don't think there was missed information," he said. "It appears that there was not any evidence that would have been discoverable during an interview for a visa."
He declined to discuss what specifically led investigators to conclude that the couple had radicalized independently as early as 2013, but suggested the information did not come from intercepts. Comey has said Farook had been in communication with individuals who were being scrutinized by the FBI in terrorism investigations, but that the contact he had was not enough to bring him onto the law enforcement radar.
"It's safe to say that the information about what happened prior to their marriage and to the attacks in San Bernardino was acquired through forensic investigations of these individual lives," Hurd said, adding: "These people weren't on the radar."
Multiple lawmakers raised the fact that neighbors saw suspicious activities but failed to mention them to investigators until after the attack.
"There were people who were aware of things, thought they were suspicious, but did not want to be accused of being discriminatory for reporting something," said Rep. Bob Goodlatte, R-Va., chairman of the House Judiciary Committee. He said these people saw activity around the garage that they thought was suspicious.
Asked repeatedly whether any hints could have led law enforcement to prevent the attack, Sen. Richard Burr, R-N.C. replied, "Explain to me how you do that without any bread crumbs that are obvious, without somebody that's inside a mosque, that's inside a person's family that tips you off. In this particular case there was nothing like that that gave them a reason to look at this couple sooner than after the attack."