“You better not have one f— case on your books,” one former company official says he was told by Mr. Mixon. USIS was approaching the end of its 2010 fiscal year in September.

It was a demand, former USIS officials say, that Mr. Mixon made repeatedly that year: Do what it takes to finish background checks, even if they aren’t thoroughly vetted…

At least eight USIS investigators whose job was to gather material for checks have been convicted of fabricating information used to push applications through.

One of them, Marcus Travers, in May pleaded guilty in U.S. District Court in Washington, D.C., to fraud for fabricating information, saying in a statement that “The mistake was made due to the pressure I felt of completing the case.”