Syed Rizwan Farook was looking for a woman. A few years ago, not long out of college, he went online to find a match. He was slim, dark-eyed, 6 feet tall and living with a parent in Riverside, his dating profiles explained.
He was Chicago-born, with Pakistani roots. He didn't drink or smoke. He avoided TV and movies, preferring instead to tinker with old cars, work out and memorize the Quran. He had a $49,000-a-year government job as a health inspector and wanted a young wife who shared his Sunni Muslim faith.
"Someone who takes her religion very seriously and is always trying to improve her religion and encouraging others to do the same using hikmah (wisdom) and not harshness," he wrote on BestMuslim.com, one of several dating and matrimonial sites he used.
In Southern California's relatively liberal Muslim community, his preference for extreme traditionalism narrowed his choices. The woman he found online and married, Tashfeen Malik, had spent her life in Pakistan and Saudi Arabia and concealed her face with a veil.
A Pakistani national, she might have seemed an answer to his longings, matching, if not exceeding, him in religious devotion. Among the many mysteries: Did she corrupt her husband, or vice versa? Did their dynamic as a couple give rise to an act of mass terror neither would have contemplated alone?
Last year, Farook brought her to the United States on a K-1 visa, also known as a "fiancee visa." Farook would say it was his wife's conservatism that attracted him. She stayed home rather than worked. She opted not to drive. He didn't want her talking to men, and she dutifully avoided their company. Even to other men in his family, her face was hidden.
The couple lived quietly in a brown, rented two-story townhouse in Redlands, an intensely private pair in their late 20s who drew little notice from neighbors. To their landlord, they seemed model tenants.
On Wednesday morning, they left their 6-month-old daughter with Farook's mother, who lived upstairs. They retrieved combat rifles and handguns from a large arsenal they had been secretly amassing.
Farook briefly joined his co-workers for their holiday potluck, before leaving. He returned with his wife. Together, wearing masks and black tactical gear and carrying those weapons, they stormed into the party, killing 14 people and wounding 21 others. Sometime before the shooting began, Malik went on Facebook to express fealty to Islamic State.
That much authorities believe they know about the massacre, which the FBI is investigating as an act of terror — the deadliest on American soil since 9/11, as well as the deadliest mass shooting since the schoolhouse murders in Newtown, Conn., three years ago.
But much remains puzzling about the case, including the specifics of the couple's radicalization. It may be weeks, or months, before investigators — who seized computers and cellphones that belonged to the couple and are working to reconstruct their communications — are able to trace a detailed path between their online meeting and their deaths, soon after the murders, in a shootout with police.
The stash of weapons discovered at the Redlands townhome —- including thousands of rounds of ammunition, a dozen pipe bombs and a workshop to make more — suggests to the FBI that the couple had been planning a terror mission for some time.
And two crushed cellphones, found in a trash can near the townhome, suggested the couple hoped to hide whoever they had been in touch with. Of particular interest to investigators is whether the couple received weapons training overseas, possibly in Pakistan, where both had spent time in recent years.
But the FBI said it had not been watching them prior to the massacre and had received no advance warning they were dangerous.
Farook, 28, grew up in Southern California, and he was in his late teens when his mother filed for divorce from his father, claiming in court papers that he drank and was abusive.
Farook earned a bachelor's degree in environmental health from Cal State San Bernardino in 2010. His older brother, Syed Raheel Farook, served in the Navy from 2003 to 2007, winning medals for service in the "Global War on Terrorism."
Among his co-workers at the San Bernardino County Public Health Department, where he worked as a restaurant inspector, Farook seemed to make little impression beyond his quiet good manners. He was "a very isolated, introverted individual with really no friends that we could identify," said David Chesley, an attorney for Farook's family.
A federal law enforcement official has said Farook had contact with overseas terror organizations, including the al-Qaeda-aligned Nusra Front in Syria and Shabab in Somalia. By the evidence of family, co-workers and acquaintances who have spoken publicly so far, however, Farook did not seem to be a man plotting jihadist violence.
In a recent discussion with a co-worker, an outspoken Messianic Jew named Nicholas Thalasinos, Farook condemned Israel but apparently did not raise alarms by his manner, said a friend to whom Thalasinos relayed the conversation. Thalasinos, 52, was among the murdered.
Malik, 29, was born in Pakistan to an affluent, land-owning, politically influential family in Karor Lal Esan, in the southern part of the country's Punjab province, a generally poor agricultural area where religious schools are known as incubators of Islamist extremism.
Though Malik's family moved to Saudi Arabia when she was a child, she returned to southern Punjab a few years ago to study pharmacology at Bahauddin Zakariya University in Multan.
One of her professors, Dr. Nisar Hussain, recalled her as "a very hardworking and submissive student," and "an obedient girl." He said she came to school veiled.
"She was religious, but a very normal person as well," Hussain said in an interview. "I cannot even imagine she could murder people."
She was a good student, he added, and at one point was first in her class. "I don't think she had any kind of mental illness. She was among the best students, always hardworking, never created problems. Yes, she was religious, but not an extremist. She never tried to influence the class in the name of religion — never."
A family member in Pakistan who asked not to be identified said that she had been a "modern girl" who changed during college.
"After a couple of years in college, she started becoming religious. She started taking part in religious activities, and also started asking women in the family and the locality to become good Muslims," the family member said. "She used to talk to somebody in Arabic at night on the Internet. None of our family members in Pakistan know Arabic, so we do not know what she used to discuss."
After university, Malik returned to Saudi Arabia, where Farook met her during a religious pilgrimage, according to his family's attorneys.
The family member said that Malik, after moving to the U.S., began posting messages of religious extremism on her Facebook account, a source of concern for her family in Pakistan.
Malik's paternal aunt, Hafza Batool, told the BBC that the family was in a state of shock. "She was so modern. I do not know what had happened to her. She brought a bad name to our family," she said.
To obtain the K-1 visa and the conditional green card that permitted her to live in the United States, Malik had to undergo background checks by the FBI and the Department of Homeland Security, but authorities apparently turned up nothing that gave them pause.
Farook told acquaintances that he and Malik were married in Saudi Arabia, in the holy city of Mecca. The couple held a post-wedding celebration at the Islamic Center of Riverside. There was a feast of rice and chicken curry.
It was there that Nizaam Ali, 23, who attends the mosque and recalled Farook as "a very nice person," said he saw Malik for the first time. She was covered, head to toe. He saw her a few other times but could not remember even seeing her hands.
"If you asked me how she looked, I couldn't tell you," Ali said.
Farook's family attorneys say she spoke Urdu and broken English. They say Farook's family was shocked to hear of the couple's involvement in the shootings, and had no advanced inkling of it.
FBI Director James Comey said that there was no evidence that the couple was directed by a larger terror network, although there were signs of "potential inspiration by foreign terrorist organizations."
"The Internet allows the opportunity for people to consume poison and radicalize," Comey added.
The answers to how that radicalization developed, the FBI hopes, lie somewhere in the pile of evidence agents seized from the couple's Redlands townhome.
After the agents departed, there was little that could be called a clue, just a baby crib, some dirty dishes, and other trappings of an ordinary-seeming domestic life.
2:15 p.m., Dec. 6: This article was updated with details about items in the townhome as well as information about the time Farook spent at Cal State Fullerton.
The youngest was 26, the oldest 60. Several had fled war-torn countries to make a better life in America. Here are the 14 people killed by Farook and Malik: