The FBI spent 10 months investigating Omar Mateen in 2013 and 2014 — including secretly recording his conversations and monitoring his Internet communications — after the Orlando nightclub killer had claimed to co-workers that he had “family connections to al-Qaida” and made "inflammatory" statements that raised concerns about possible ties to terrorism, FBI Director James Comey said today.

The FBI closed out that probe in May 2014 after Mateen, during the course of two FBI interviews, told agents he had made those statements “in anger” because he thought his co-workers were discriminating against him and were “teasing him because he was a Muslim,” Comey said.

Comey revealed those details — as well as evidence uncovered during a second aborted FBI probe of Mateen that took place just a few months later — during the course of a news conference at bureau headquarters. He told reporters that the FBI’s investigation has uncovered “strong indications” that Mateen had become radicalized and potentially inspired by foreign terrorist groups, Yahoo reports.