Washington, Nov 23 (IANS): Confessed Pakistani-American terrorist, David Coleman Headley was a wildly elusive figure who juggled allegiances with militant groups and security agencies, manipulating and betraying wives, friends and allies, according to a new investigative report.

Questions still persist about the Lashkar-e-Taiba operative and ISI spy despite his unprecedented confessions at a trial in Chicago revealing the Pakistani spy agency, the Inter-Services Intelligence Directorate's role in the Mumbai terror attacks, ProPublica, an investigative media group said.

But the trial shed little light on Headley's past as a US Drug Enforcement Administration (DEA) informant and the failure of US agencies to pursue repeated warnings over seven years that could have stopped his lethal odyssey sooner - and perhaps prevented the Mumbai attack, it said.

Former Indian Home Secretary G.K. Pillai asserted during an interview in Delhi that US authorities know more about Headley than they have publicly stated, the investigative report said.

It also cited several senior Indian security officials as saying they believe that US warnings provided to India before the Mumbai attacks came partly from knowledge of Headley's activities. They believe he remained a US operative.

"David Coleman Headley, in my opinion, was a double agent," Pillai was quoted as saying. "He was working for both the US and for Lashkar and the ISI."

ProPublica cited US and foreign officials as saying say Headley's role as an informant or ex-informant helped him elude detection as he was training in Pakistani terror camps and travelling back and forth to Mumbai to scout targets.

However, DEA officials told ProPublica that Headley's relationship with the anti-drug agency was more limited than has been widely described.

The DEA officially deactivated Headley as a confidential source on March 27, 2002, according to a senior DEA official cited by the report. That was weeks after he began training in Lashkar terror camps in Pakistan and six years before the Mumbai attacks.

But Officials at other US agencies say Headley remained a DEA operative in some capacity until as late as 2005. Headley has testified that he did not stop working for the DEA until September 2002, when he had done two stints in the Lashkar camps.

ProPublica also cites some US officials as saying the government ended Headley's probation for a drug conviction three years early in November 2001 to shift him from anti-drug work to gathering intelligence in Pakistan.