In the final few years of Tashfeen Malik's life, the people around the young woman saw her dress ever more conservatively and urge people ever more ardently to live a devout life.

For an aunt in Malik's old hometown of Pakistan, Malik's growing religious focus was one of the last things the aunt heard about her 29-year-old niece — before last week, when the relative learned that her niece and her niece's husband had donned face masks, hoisted assault rifles and killed 14 people in a rampage in California.

"I recently heard it from relatives that she has become a religious person, and she often tells people to live according to the teachings of Islam," recalled aunt Hifza Batool.

Malik's path from Pakistan to the bloody events of this past week — when she and her husband slaughtered people gathered for a holiday work party — remains a mystery.

Officials from the U.S. Federal Bureau of Investigation, family lawyers and others said they know little about the housewife and mother, apart from what came to light on Friday: that Malik had pledged allegiance to the Islamic State group on Facebook as she and her American-born husband, Syed Farook, 28, launched the massacre.

The husband and wife were killed in a shootout with police hours after they opened fire on a gathering of Farook's colleagues.

The FBI said it is investigating the rampage as a terrorist attack.

President Barack Obama plans to deliver an address to the nation Sunday night on the attack and the government's efforts to keep the nation safe.

Early on Saturday, authorities with guns drawn raided a home next door to the house where Farook's family used to live in California, breaking windows and using a cutting torch to get into the garage, neighbors said.

The FBI would not say what it was looking for, but a neighbor said an old friend of Farook's lives there.

More than three years ago, that person bought the two assault rifles later used in the shooting, but authorities haven't been able to talk to him because he checked himself into a mental hospital after the attack, said a law enforcement official who was not allowed to discuss the investigation and spoke on condition of anonymity.

The FBI has said the man is not a suspect in the shootings, though they want to question him.

U.S. officials said Farook had been in contact with extremists via social media. One official said those contacts were not recent and did not involve any significant players on the FBI's radar.

Farook was born in Chicago to Pakistani parents and raised in California. Malik arrived in the U.S. in 2014 on a Pakistani passport and a fiancee visa but had spent extended periods of time in Saudi Arabia.

Saudi Interior Ministry spokesman Maj. Gen. Mansour Al-Turki told The Associated Press that authorities there have received no indication Malik was radicalized in Saudi Arabia.

Al-Turki said Saudi records show she was not a resident of Saudi Arabia and had been to the kingdom only twice. On both trips, she came to visit her family, once in 2008 for several weeks and the second time in 2013 for four months.