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Lying through his teeth about his past - he claimed to be living in Kuwait when the First Gulf War broke out and provided detailed accounts of how he got out of there. . . except some of them were impossible because they got the chronology of major events in the war wrong by months or involved fleeing into combat zones
*
Almost certainly lying about his present - he claimed to be a med student in India, and that he was asked to help with the autopsy of an Afghani minor who died from rape related injuries. I am willing to believe the Afghan government would ask foreign doctors for help under those circumstances (remember, this was around 2015 when the US backed president was still in power) to give the autopsy some credibility. I am not willing to believe they would request or even allow a trainee to help when the rape got international attention. This was on top of other claims to be directly involved in any number of medical relief/disaster response efforts even though it was impossible to fit those in alongside an alleged 90 hours / week of residency work.
* Plagiarizing alleged hate mail.
This was FTB's stated reason for getting rid of him rather than the serial, implausible fabrications.