Breaking News Emails Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings. 
 
 Dec. 8, 2015, 9:51 PM GMT / Updated Dec. 9, 2015, 1:27 AM GMT By Pete Williams, Hannah Rappleye, Richard Esposito, Andrew Blankstein and Robert Windrem 
 
 San Bernardino terror couple Syed Rizwan Farook and Tashfeen Malik spent at least a year preparing for their terror attack, NBC News has learned, practicing at a local gun range and making financial plans for their family after their deaths. 
 
 And the husband may have discussed an attack as many as three years ago, law enforcement sources said Tuesday. 
 
 Two sources said Farook and Malik had practiced their shooting skills at a Riverside, California-area gun range for a year or more before last Wednesday’s attack on a holiday office party. They killed 14 people and wounded 21 more with firearms at the Inland Regional Center in San Bernardino. 
 
 Counterterrorism officials also told NBC News that Farook and Malik were making preparations for some time to “take care of both grandma and the baby.” The couple lived in a Redlands, California residence with their 6-month-old daughter and Farook’s 62-year-old mother, Rafia Farook. They left their daughter with Rafia Farook on the morning of the attack. 
 
 Investigators are examining a $28,500 deposit made to Farook’s bank account in the weeks before the Dec. 2 rampage. 
 
 A U.S. counterterrorism official said that he didn’t have details on the transfer, but that it “would be consistent with them making preparations for grandma and the kid.” 
 
 “They had purposely thought through that problem,” said the official. “There were other indications of preparations.” 
 
 Reuters reported that the loan to Farook was made by the online lender Prosper. In a statement, Prosper said that the company is "prohibited by law from disclosing any non-public, personally identifiable information regarding any loan originated through our platform." 
 
 "All loans originated through the Prosper platform are subject to all identity verification and screening procedures required by law, including U.S. anti-terrorism and anti-money laundering laws," the spokesperson said. "Like all Americans, Prosper is shocked and saddened by recent events in San Bernardino." 
 
 And a senior law enforcement official told NBC News Tuesday that FBI investigators have been told that Farook discussed staging an attack in California as early as 2012. 
 
 The official said investigators don’t yet know what to make of the claim, although they say it may bolster their growing suspicion that Farook was radicalized long before he returned from Saudi Arabia last year with his wife. 
 
 The latest revelations come after NBC News reported Monday that federal investigators are interviewing a neighbor of Farook and Malik who bought two of the four guns that were used in the massacre. ||||| (CNN) More than one week later, authorities are still digging to make sense of the San Bernardino massacre, piecing together the clues they've compiled so far and trying to discover more, including by investigating the shooters' electronic trail and searching a lake near where the carnage occurred. 
 
 The identity of the killers, Syed Rizwan Farook and Tashfeen Malik, is not in doubt. But investigators want to find out more about who this married couple interacted with, how they hatched and carried out the plot, and why. 
 
 These are the latest and most significant investigative leads so far: 
 
 Friday 
 
 Friend of killer says he helped build prior pipe bombs 
 
 Enrique Marquez, a former neighbor of Farook, told investigators he and his friend previously built pipe bombs, law enforcement officials said. 
 
 Marquez said he had nothing to do with devices found at the home of Farook and Malik, or the ones that apparently failed to go off at the site of the shooting, the officials said. 
 
 Marquez, who has spent several days being voluntarily interviewed by the FBI, portrayed the two men as hobbyists experimenting with building the devices, the officials told CNN. 
 
 He also boasted, one official said, that if he had made the bombs they would have gone off. 
 
 Marquez has emerged as a person of interest in the San Bernardino shootings because he bought rifles used in the attack. He has not been charged with a crime. 
 
 Divers search a small lake near where shooters had been, the FBI says 
 
 Divers ended Friday evening a second search of a small lake in a park a few miles from San Bernardino's Inland Regional Center, where 14 people were killed last week. 
 
 David Bowdich, the assistant director in charge of the FBI's Los Angeles office, wouldn't comment on what they were looking for. But he said Farook and Malik were in the area "at some point," without specifying if this was before or after the massacre. 
 
 One of the items divers likely are looking for is a missing hard drive from the couple's computer. 
 
 Bowdich has said the search will take several days. 
 
 Thursday 
 
 Farook was in the same 'social circle' as convicted terrorist, FBI believes 
 
 The FBI believes Farook had ties to a group of jihadists in California who were arrested in 2012 for attempting to travel to Afghanistan to join al Qaeda. 
 
 Specifically, investigators are taking a new look at one of the four men who was arrested in the 2012 case, Sohiel Kabir. Kabir, who was convicted and sentenced to 25 years in prison, was the recruiter who helped radicalize others. 
 
 The 2012 probe happened in Riverside, California, not far from San Bernardino. Farook was in the social circle of Kabir, officials told CNN. 
 
 The FBI initially investigated five men as part of the Riverside group. The fifth wasn't arrested and hasn't been identified. But Farook was not among those investigated at the time, the officials said. 
 
 Wednesday 
 
 Marquez says Farook considered terror plot in 2012 
 
 Marquez told investigators that he and Farook conceived a terror plot in 2012, but abandoned their plans after the FBI arrested an unrelated group in Riverside that had been planning to join al Qaeda in Afghanistan. 
 
 Marquez checked himself in to a mental health facility after the San Bernardino attack. 
 
 He is cooperating with the FBI, but investigators are still trying to corroborate the information he has provided, including details of the alleged 2012 plot. 
 
 Marquez claims he knew nothing about the San Bernardino shootings. He has not been charged with a crime. 
 
 That same friend's marriage -- to a woman of Russian descent -- is under scrutiny 
 
 Now that Farook's friend and former neighbor Enrique Marquez has the attention of investigators, his own relationships are being scrutinized. 
 
 Federal authorities are "examining the circumstances of the marriage" between Marquez and a woman of Russian descent, according to a source familiar with the matter. Investigators are looking into whether this was a sham marriage for immigration purposes. 
 
 The woman came to the United States from Russia on a J-1 visa in 2009, according to another law enforcement official. That official said the woman did not appear for an interview earlier this week for her permanent resident application. 
 
 The FBI has recovered some electronic communication from killers, officials say 
 
 Farook and Malik tried to destroy their electronic tracks, but the FBI has been able to recover some of those communications, two law enforcement officials told CNN. 
 
 FBI Director James Comey told a Senate hearing Wednesday the agency has found online discussions about jihad between Farook and Malik from late 2013, before they began dating. Investigators have found data on a tablet computer and other cell phones at the couple's home, he said. 
 
 The FBI is still trying to recover information from two smashed cell phones found in a garbage can near the home. They also have not found the hard drive from a computer at the home; investigators believe the hard drive was removed as a way to cover up the crime. 
 
 The shooters talked about jihad and martyrdom before marrying, FBI leader says 
 
 The online communications recovered so far indicate that the two killers had become radicalized long before carrying out last week's attack. 
 
 Comey elaborated a bit on the conversations between Farook and Malik, where they talked to each other about jihad and martyrdom before they were married and before Malik immigrated to the United States. 
 
 Asked if Malik was radicalized before she entered the United States, Comey replied: "So far, it looks like she was... she was before she connected with the other killer." 
 
 Tuesday 
 
 Authorities say Farook's friend, Marquez, bought weapons used in the rampage 
 
 The two AR-15s used in the San Bernardino attack were purchased by Enrique Marquez for Farook back in 2011 and 2012, two law enforcement officials said. Marquez acknowledged that he bought the weapons and soon after gave them to Farook, though he never reported the ownership transfer. Such transactions could be a violation of California law, the officials said. 
 
 Farook borrowed $28,500 via online lender Prosper last month 
 
 Farook took out a loan for $28,500 in November, multiple law enforcement officials told CNN. Investigators have accounted for all the money and do not believe any of the money was provided to the killers by any outside entity backing the plot, according to one of the sources. 
 
 Because of that, the officials said the loan, from the online lender Prosper, is not considered of significant investigative value at this stage. 
 
 About half was given to Farook's mother in the last couple of weeks, one official said and some was spent on household items. 
 
 It is believed the couple had bought the arsenal they used before the loan was taken out. 
 
 A representative for Prosper would not confirm the existence of the loan, but provided CNN the following statement: "Prosper is prohibited by law from disclosing any non-public, personally identifiable information regarding any loan originated through our platform. All loans originated through the Prosper platform are subject to all identity verification and screening procedures required by law, including US anti-terrorism and anti-money laundering laws. As part of our standard procedures, we also confirm that all loan funds are disbursed into a verified US bank account in the borrower's name. Like all Americans, Prosper is shocked and saddened by recent events in San Bernardino." 
 
 A man thought to be Farook went to a gun range -- alone -- days before the attack, a source says 
 
 A man believed to be Farook visited the Magnum Shooting Range in Riverside, California, alone on the Sunday and Monday prior to the December 2 attacks in San Bernardino, according to a source familiar with the matter. 
 
 He practiced shooting an AR-15. The source said sign-in logs at the range were paired with surveillance video that have been turned over to the FBI. The FBI was at the range Monday night asking questions and showing pictures of another male (not Farook), asking if that man had ever been to the range. 
 
 Last week 
 
 Officials: While the shooting was happening, Malik pledged allegiance to ISIS in a Facebook post 
 
 As the San Bernardino attack was happening, investigators believe Malik posted on Facebook pledging allegiance to ISIS leader Abu Bakr al-Baghdadi, three U.S. officials familiar with the investigation told CNN. 
 
 Malik posted the comment, but it was made on an account with a different name, one U.S. official said. The officials did not explain how they knew Malik made the post. 
 
 "There was a post that went up around 11 a.m. PT on the account Wednesday that violated the company's community standards (those standards prohibit people using Facebook to promote terrorism or celebrate/glorify violence)," a Facebook official told CNN. "It was taken down Thursday. He said he couldn't go into details about the nature of the post other than it violated standards (pointed to their standards prohibiting terrorism). The official said Facebook is cooperating with law enforcement." 
 
 Authorities think the couple met in 2013 in Saudi Arabia during the Hajj 
 
 Farook traveled to Saudi Arabia in 2013 for the Hajj for a couple of weeks, two government officials said. 
 
 One of the officials explained that this is a common occurrence and the trip would not have raised any red flags as many Americans travel to Saudi Arabia during that time. 
 
 The feds believe Farook met Malik during that trip. Malik eventually came to the United States on a fiancée visa, the official said. She then obtained a green card. ||||| Late Friday, a UPS driver noticed that a package being delivered was addressed to Farook's townhouse and turned around to return it to a distribution facility, San Bernardino Police Chief Jarrod Burguan said in a tweet. The package was held in isolation, and the sheriff's office deployed bomb technicians to inspect the package out of an abundance of caution. 
 
 [Previous story, published Friday, 10:06 p.m. ET] 
 
 (CNN) -- The San Bernardino, California, mass shooting is now being investigated as "an act of terrorism," FBI official David Bowdich said Friday. 
 
 Bowdich said the FBI "uncovered evidence ... of extreme planning." 
 
 He said some phone conversations between at least one of the shooters and other people are being investigated. The announcement means the FBI has become the lead investigative agency, taking over from San Bernardino police. 
 
 "As of today, based on the information and the facts as we know them, we are now investigating these horrific acts as an act of terrorism," said Bowdich, assistant director of the FBI office in Los Angeles. 
 
 JUST WATCHED Who's the female San Bernardino killer? Replay More Videos ... MUST WATCH Who's the female San Bernardino killer? 02:45 
 
 The announcement came several hours after a revelation about Tashfeen Malik, the female shooter in the Wednesday massacre that left 14 dead and 21 wounded. 
 
 She posted a pledge of allegiance to ISIS leader Abu Bakr al-Baghdadi on Facebook while the shooting was happening, three U.S. officials familiar with the investigation told CNN. 
 
 Malik's post was made on an account with a different name, one U.S. official said. The officials did not explain how they knew Malik made the post. 
 
 A Facebook official told CNN that a post that went up about 11 a.m. Wednesday that violated the company's community standards that prohibit the promotion of terrorism or the glorification of violence. It was taken down Thursday. 
 
 The official said he couldn't go into details about the nature of the post. The official said Facebook is cooperating with law enforcement. 
 
 The mass shooting may have been inspired by ISIS, a law enforcement official said, but none of the officials said ISIS directed or ordered the attack. ISIS has called for people worldwide to launch attacks in its name but isn't known to have claimed credit for what happened in San Bernardino. 
 
 JUST WATCHED Gunman's sister: He was shy and quiet Replay More Videos ... MUST WATCH Gunman's sister: He was shy and quiet 02:06 
 
 Malik and her husband, Syed Rizwan Farook, burst into a holiday party for the environmental health department he worked for and opened fire. They were killed elsewhere in a shootout with police. 
 
 No one has been arrested in connection with the massacre, but authorities say arrests are possible. 
 
 "This is looking more and more like self-radicalization," a law enforcement official said. 
 
 Farook's relatives didn't know the couple held radical views and have no idea why the couple burst into the party for Farook's co-workers and viciously opened fire, family lawyers said. Nor did the family know the couple had a makeshift bomb lab in the apartment they shared with their 6-month-old daughter and Farook's mother. 
 
 "It just doesn't make sense for these two to be able to act like some kind of Bonnie and Clyde or something," Farook family attorney David S. Chesley told CNN's Chris Cuomo. "It's just ridiculous. It doesn't add up." 
 
 Another official said authorities haven't ruled out that others may have influenced this radical view. In addition, the law enforcement source said investigators think a workplace issue with religion may have sparked the killings. 
 
 Officials: Farook talked to person investigated for terror 
 
 Neither Farook nor his wife had gotten into trouble with the law, according to police. Neither was on any list of potentially radicalized people. 
 
 But it's not known what connections Malik, who was born and raised in Pakistan and moved to Saudi Arabia about the age of 19, had with any terrorists or groups. 
 
 Investigators are exploring Farook's communications with at least one person who was being investigated for possible terror connections. Some were by phone, some on social media. 
 
 "These appear to be soft connections," an official said, meaning they were not frequent contacts. Farook's last communication with the contacts was months ago. 
 
 A federal official said Farook has "overseas communications and associations," but it's not yet clear how relevant they are to the shootings. "We don't know yet what they mean," the official said. 
 
 Family lawyer Mohammad Abuershaid said that Farook traveled twice to Saudi Arabia -- first in 2013 for the Hajj, the annual pilgrimage to Mecca that Muslims are required to make at least once in their lifetimes, then again to marry Malik, whom he'd met through an online dating service. 
 
 Bowdich said that he went to Pakistan, as well, though Abuershaid denied that. 
 
 Did a workplace dispute boil over? 
 
 The shooters didn't make it easy for authorities: The hard drive from their computer is gone, and two relatively new cell phones were found smashed in a garbage can near one of the crime scenes, law enforcement officials said. 
 
 Bowdich called this an attempt to destroy "digital fingerprints." 
 
 Photos: San Bernardino shooting Police officers stand guard as they investigate a suspicious vehicle in Redlands, California, on Wednesday, December 2, after a mass shooting in nearby San Bernardino in which 14 people died and 21 were injured. The shooting took place at the Inland Regional Center, where employees with the county health department were attending a holiday event. The two shooters -- Syed Rizwan Farook and his wife, Tashfeen Malik -- were fatally shot in a gun battle with police hours after the initial incident. Farook worked for the county health department. Hide Caption 1 of 29 Photos: San Bernardino shooting A police officer places a marker along East San Bernardino Avenue, near where the shootout occurred. Hide Caption 2 of 29 Photos: San Bernardino shooting Law enforcement officers search a residential area for suspects who fled after the shooting. Hide Caption 3 of 29 Photos: San Bernardino shooting Police search for the suspects in San Bernardino. Hide Caption 4 of 29 Photos: San Bernardino shooting The residential area was not far from where the shooting occurred. Hide Caption 5 of 29 Photos: San Bernardino shooting Law enforcement officers search a neighborhood in San Bernardino. Hide Caption 6 of 29 Photos: San Bernardino shooting A police officer loads his weapon while pursuing suspects. Hide Caption 7 of 29 Photos: San Bernardino shooting A SWAT team mobilizes during the search. Hide Caption 8 of 29 Photos: San Bernardino shooting People pray on the San Bernardino Golf Course, across the street from where the shooting took place. Hide Caption 9 of 29 Photos: San Bernardino shooting Heavily armed law enforcement officers swarmed the area where the shooting occurred. Hide Caption 10 of 29 Photos: San Bernardino shooting People leave a community center after reuniting with friends and family in the aftermath of the shootings. Hide Caption 11 of 29 Photos: San Bernardino shooting A woman is comforted near the scene of the shooting. Hide Caption 12 of 29 Photos: San Bernardino shooting A police helicopter hovers around the Inland Regional Center. Hide Caption 13 of 29 Photos: San Bernardino shooting Luis Gutierrez gets emotional as he talks about his wife who works in the facility and saw a gunman, according to Los Angeles Times photographer Marcus Yam. Hide Caption 14 of 29 Photos: San Bernardino shooting Two women speak with a firefighter at a triage area near the scene. Hide Caption 15 of 29 Photos: San Bernardino shooting Police stand guard outside of the emergency room at the Loma Linda University Medical Center, where some of the victims were being treated. Hide Caption 16 of 29 Photos: San Bernardino shooting Police escort civilians away from the site of the shooting. Hide Caption 17 of 29 Photos: San Bernardino shooting People walk away from the scene. It is unclear how many people were at the facility at the time of the shooting. Hide Caption 18 of 29 Photos: San Bernardino shooting Police in SWAT gear secure the area. Hide Caption 19 of 29 Photos: San Bernardino shooting Two women embrace at a community center where family members were gathering to pick up people from the scene. Hide Caption 20 of 29 Photos: San Bernardino shooting People gather at the San Bernardino Golf Course. Hide Caption 21 of 29 Photos: San Bernardino shooting People talk to police at the golf course. Hide Caption 22 of 29 Photos: San Bernardino shooting A woman is wheeled away on a stretcher. Hide Caption 23 of 29 Photos: San Bernardino shooting People are moved away from the area by bus. Hide Caption 24 of 29 Photos: San Bernardino shooting Police and fire personnel are seen near the site of the shooting. Hide Caption 25 of 29 Photos: San Bernardino shooting A crowd gathers behind the police line. Hide Caption 26 of 29 Photos: San Bernardino shooting Ambulances pull out of a staging area near the Inland Regional Center. Hide Caption 27 of 29 Photos: San Bernardino shooting A SWAT vehicle carries police officers. Hide Caption 28 of 29 Photos: San Bernardino shooting SWAT teams and a bomb squad were working to clear the buildings where the shootings took place. Hide Caption 29 of 29 
 
 Authorities haven't ruled out what President Barack Obama called "mixed motives," meaning that Islamic radicalism and workplace grievances both could have driven the attack. 
 
 San Bernardino Police Chief Jarrod Burguan had earlier said there were indications Farook appeared angry when he suddenly left the holiday luncheon at Inland Regional Center, only to return heavily armed with his wife. 
 
 But the chief on Friday played down that possibility, saying many people at the holiday party said they saw no evidence of an argument. 
 
 Farook family lawyers didn't speculate on his reasoning, though Chesley did say that "at some times co-workers have done silly things, like made fun of Syed's beard." 
 
 One of Farook's colleagues killed in the attack, Nicholas Thalasinos, liked to discuss religion and politics. Farook and Thalasinos, reportedly a devout Messianic Jew, had a "heated, passionate" discussion about politics and religion a few days earlier, said Kuuleme Stephens, a friend of Thalasinos, who called him at work while Thalasinos was in the middle of the conversation. 
 
 The men were sticking by their strongly held positions but were not fighting, Stephens said. 
 
 Thalasinos' widow, Jennifer, said he was quite verbal about terrorism. "He's very upset about what ISIS has been doing and the radicalized Muslims," she said. 
 
 Reporters go inside attackers home 
 
 JUST WATCHED Take a look inside the San Bernardino shooters' home Replay More Videos ... MUST WATCH Take a look inside the San Bernardino shooters' home 01:49 
 
 Even those who knew Farook best didn't see anything to suggest something nefarious, according to family representatives. 
 
 That included Farook's mother, who thought nothing of it when the pair had her watch their 6-month-old girl while they went to a doctor's appointment, Abuershaid said. The lawyer didn't know if there ever was a doctor's appointment -- only that the mother initially worried that Farook had gotten shot, not that he was doing the shooting. 
 
 Chesley expressed surprise that Malik, whom he described as being "about 90 pounds, so it's unlikely she could even carry a weapon or wear some type of a vest or do any of this," could have been an active participant in the horror. 
 
 A mob of reporters was allowed inside Farook and Malik's rented Redlands townhouse Friday, getting a glimpse at how they lived. 
 
 Much of it appeared relatively mundane -- from a hanging clock to couches to many baby items like a crib, ExerSaucer and other toys. 
 
 But there were also hints of something more, like shattered glass, boarded-up windows and lists of items seized by federal authorities. The FBI always leaves behind such lists after a search. 
 
 Authorities searched the house earlier and found pipe bombs, thousands of rounds of ammunition inside the house and more guns. 
 
 The FBI inventoried what they found and returned custody of the home to the landlord. The inventory listed parts for guns, about 5,000 rounds of ammunition, tools, gun boxes, holsters, electronics, Christmas lights, a thumb drive, a laptop and a cellphone with a SIM card missing. 
 
 Asked whether authorities were concerned about media entering the couple's apartment, Bowdich replied: "Once we turn that location back over to the occupants of that residence or once we board it up, anyone who goes in at that point has nothing to do with us."
– San Bernardino shooter Syed Rizwan Farook may have been planning mass murder even before he married accomplice Tashfeen Malik, according to sources close to the investigation. Officials tell CNN that Farook plotted to carry out an attack with somebody else in California in 2012, though it's not clear how far the preparations went. The plan was called off after a round of terror-related arrests in the area "spooked" Farook and his accomplice, one source says. Law enforcement officials tell NBC News that Farook and Malik appeared to have planned the San Bernardino attack for at least a year, training at local gun ranges and making financial arrangements for their 6-month-old daughter and Farook's mother. The FBI is still investigating a loan of $28,500 deposited into Farook's account two weeks before the attack, a loan that an investigator tells NBC "would be consistent with them making preparations for Grandma and the kid." In other developments: The Los Angeles Times reports that former Minneapolis resident Mohamed Abdullahi Hassan, an alleged ISIS recruiter who targeted Westerners on social media, has surrendered to authorities in Somalia. Investigators suspect he may have influenced Farook. The San Bernardino Department of Public Health, which employed Farook and most of the 14 people killed in the attack, trained employees last year for an active-shooter drill in the same room at the Inland Regional Center that Farook and Malik attacked, the AP reports. "Everyone was trying to be quiet and not draw attention to themselves as they were trained to do, to try to find as much protection as you can," an assistant director of the department says. "Unfortunately, the room just didn't provide a whole lot of protection." Law enforcement sources tell the Times that a device Farook and Malik left behind at the scene of the attack may have been designed to kill first responders. The sources say the crude device, which included three pipe bombs, was disabled by water from the building's sprinkler system. See a photo of the holiday party taken just before the shooting here.