NEW YORK • Tashfeen Malik remains largely a mystery to both investigators and her relatives in Pakistan, who have responded to her actions with shock and horror.
Officials said Malik pledged allegiance to the Islamic State in Iraq and Syria group in a Facebook status posted on the day of the attack, but they cautioned that there was no evidence that the terrorist group had directed the rampage.
Relatives in Pakistan who spoke to reporters in the days after the attack described Malik, 29, as a bright and religious young woman who appeared to have a promising future.
"All relatives here are shocked to hear about it," said Mr Javed Rabbani Aulakh, an uncle of Malik's in Pakistan. She was conservative, he said, but appeared to have no interest in extremism.
Malik moved to Saudi Arabia with her father when she was young, her relatives told reporters, after an inheritance dispute between her father and their extended family led to a bitter falling out.
The relatives said they believed it was there that both father and daughter developed radical political and religious beliefs.
"From what we heard, they lived differently, their mindset is different," Ms Hifza Bibi, a stepsister of Malik's father, told Reuters. She said the family was originally "from a land of Sufi saints", a reference to a mystical and open-minded interpretation of Islam that is looked upon with scorn by more conservative or radical adherents of the faith.
Ms Bibi said Malik's father cut himself off from the rest of the family after he moved to Saudi Arabia. "He doesn't care about anyone here. A man who didn't come to attend his own mother's funeral, what can you expect from him?"
Despite her father's estrangement from relatives in Pakistan, Malik returned to the country in 2007 to pursue a degree in pharmacology at Bahauddin Zakariya University in the city of Multan.
Dr Nisar Hussain, one of Malik's professors, said she had been a gifted student who, at one point, was at the top of her class in the university's department of pharmacology, according to The Los Angeles Times.
"She was religious, but a very normal person as well," said Dr Hussain. He said he did not believe Malik "had any kind of mental illness".
One relative, who spoke to The Los Angeles Times on the condition of anonymity, said that Malik's religious beliefs seemed to change during her time at the university and that relatives sometimes worried about her radical postings on social media.
Malik also began to talk online with friends in Arabic, a language that her family members in Pakistan did not speak, according to the relative.
Malik left school in 2012 and moved to the United States two years later after she met Farook, an American citizen living in California, on a dating website.
She was granted a K1 visa, also known as the fiancee visa, in Pakistan in July last year and travelled to the US that month.
NEW YORK TIMES