WASHINGTON - State Department visa officers conducted all required security checks on Tashfeen Malik, one of two shooters in the San Bernardino massacre early this month, but found no "derogatory" information before granting her a visa to enter the United States in 2013, a person familiar with the documentation said.The standard security inquiries include interagency counter-terrorism screening, fingerprint checks, facial recognition analysis and checks against worldwide US consular records, a State Department source said.Because there was no derogatory information in Malik's application, visa officers had no grounds for ordering deeper investigations into her background, let alone blocking her entry when she arrived in the United States in December 2013, officials have said.The latest disclosures will likely strengthen calls in Congress to toughen the procedure for issuing visas in order to spot militants applying to enter the United States.Pakistan-born Malik came to the United States under a K-1 "fiancee" visa. She was engaged at the time to Syed Farook, a US-born citizen who together with Malik carried out the Dec. 2 shooting that killed 14 people.Consular officers ran Malik's name through US government consular and intelligence data bases, the source familiar with the documentation said. State Department sources declined to enumerate all the tests conducted before Malik's application was approved. The State Department source said the department was legally unable to discuss the contents of any individual's file.An individual's application file contains records of which security checks were carried out and the results. None of the documents in Malik's State Department file show any negative information was discovered during State Department security checks, the source familiar with the documentation said.