The woman involved in the shootings in San Bernardino, Calif., on Wednesday passed through two rounds of criminal and national security background checks as she obtained a “fiancé visa” and later a resident green card to live in the United States, federal officials said.  Those checks turned up no negative information about the woman, Tashfeen Malik, a federal official said Friday. But after the F.B.I. said Friday that it was investigating the shootings as an act of terrorism — Ms. Malik pledged allegiance to the Islamic State in a Facebook post the day of the attack — officials were scouring her immigration record to see if there were any revealing details they might have missed.  “There was nothing she presented that would have been flagged,” a federal official said, speaking anonymously to discuss a fast-moving investigation involving several federal agencies. But, he said, “We’re going back right now and double-checking and looking over everyone’s shoulder who was involved.”  The information that Ms. Malik came to live in this country legally has heightened concern about security reviews in the immigration system. It has also renewed a tense debate in Washington, particularly after the Nov. 13 terrorist attacks in Paris provoked a furor in Congress and among state governments about the vetting of refugees from Syria and Iraq.  On Thursday, two Republican senators, Ted Cruz of Texas, who is running for president, and Jeff Sessions of Alabama, demanded that the Obama administration provide them with detailed information on the immigration history of Ms. Malik, who came to the United States and married Syed Rizwan Farook, an American citizen whom officials have identified as her partner in Wednesday’s shooting that killed 14 people and injured 21.  Ms. Malik, 29, was granted a K-1 visa, also known as the fiancé visa, in Pakistan in July 2014, the officials said, and she traveled to the United States that month.  The review process for a K-1 visa is “not as strict” as the vetting for refugees, Josh Earnest, the White House spokesman, said. But immigration officials said the K-1 review was more extensive than the vetting of a foreigner who planned to only visit. Mr. Earnest said Obama administration officials were examining Ms. Malik’s journey to this country to see if any policies should be changed.  As a routine part of the visa and green card applications, Ms. Malik gave fingerprints and other identifying information, which were passed twice through background checks using the State Department’s watch lists and the immigration, counterterror and criminal databases at the Department of Homeland Security and at the F.B.I.  For the K-1 visa, Mr. Farook, 28, started the application to bring in his fiancée, who provided a Pakistani passport.  Adhering to standard procedure for the K-1 visa, Ms. Malik had to demonstrate to State Department consular officials in Pakistan that their relationship was legitimate, and that she and Mr. Farook intended to marry in the United States within 90 days after she received the visa. Mr. Farook had to prove that he and Ms. Malik had met in person at least once in the previous two years, typically done by providing photos showing them together, personal messages and travel reservations. After the 90-day period, a K-1 visa expires and cannot be renewed.  As part of that review, Ms. Malik had a personal interview with a consular officer in Pakistan, federal officials said.  The couple came to the country in July 2014 on a flight that originated in Jidda, Saudi Arabia, two federal officials said. According to a certificate obtained by The Associated Press, the two were married in Riverside County, Calif., in August 2014, within the 90-day time limit.  On Sept. 30, 2014, Mr. Farook applied for a green card to make Ms. Malik a permanent resident, based on her marriage to an American citizen. There is no limit on the number of green cards available to spouses of citizens, so the process generally moves quickly.  Since green cards are granted by a different agency, the United States Citizenship and Immigration Services, Ms. Malik had to undergo more background checks, probably providing a new set of fingerprints, officials said.  It is routine for an officer from the citizenship agency to interview both spouses, but officials there could not confirm that Ms. Malik was interviewed, citing privacy concerns.  Under the standard procedure, the couple would have had to provide documents and undergo questioning, primarily to persuade immigration officers their marriage was not fraudulent. Sometimes the officer will interview the spouses separately, asking highly personal questions about foods or pastimes the other spouse enjoyed or other intimate details, to make sure the immigrant and the spouse lived together.  Ms. Malik received a conditional green card in July 2015, officials said. After two years, the couple would have had to apply again to get a regular green card, showing they were still married.  Both were killed in a shootout with the police on Wednesday, leaving behind a 6-month-old daughter.  An earlier version of this article, using information from the police, misstated the age of Tashfeen Malik. She was 29, not 27.  A version of this article appears in print on December 5, 2015, on page A14 of the New York edition with the headline: Smooth Visa Process for Woman in Attack Is a Focus of the Inquiry. Order Reprints| Today's Paper|Subscribe
Federal officials were reviewing the immigration records of Tashfeen Malik, who came here to marry Syed Rizwan Farook and was killed after the San Bernardino massacre.