More questions are being raised about how federal law enforcement officials handled two tips they received about David Coleman Headley, the U.S. businessman and former DEA informant who has confessed to helping plot the 2008 terrorist attacks on Mumbai. The first tip came in 2005 and the second in 2007, just a year before the attacks that killed 166 people, including six Americans.

NBC News correspondent Michael Isikoff reported Saturday night that the second warning, given by one of Headley’s wives to the U.S. Embassy in Islamabad, was never passed along to the FBI in New York, according to a U.S. official who spoke with NBC. Isikoff also reported that officials didn’t consider the earlier tip sufficient enough to put Headley on the “no fly” list or to trigger a full-scale probe at the time.

ProPublica reported on Friday that the Joint Terrorism Task Force in New York had been warned in 2005 by another of Headley’s wives that he was training in Pakistan’s mountains with the terrorist group Lashkar-i-Taiba, which carried out the Mumbai attacks. She also told them that he shopped for night vision goggles and other equipment.

On Saturday law enforcement officials confirmed to ProPublica that while Headley was training with Lashkar he was also working with the DEA. Headley is the son of a Pakistani father and an American mother. He became a DEA informant in the late 1990s, after he was arrested on heroin trafficking charges.

Headley was apparently married to three women at the same time. The FBI arrested him last October, 11 months after the Mumbai attacks. In March, he pleaded guilty to charges of terrorism in the Mumbai attacks and to a failed plot to take and behead hostages at a Danish newspaper. He is cooperating with authorities.