. >> reporter: about the fbi agent who was chulpayev's handler, donte jackson, now under investigationmurder case while receiving extravagant gifts from his informants. >> it is nice to have an fbi agent that's looking over your shoulder i guess. >> reporter: our abc news "nightline" investigation began months ago in fort lauderdale, a place where people come to have fun, and where a party van cruising down a1a seemed to fit in, which is why we chose to use it. as the perfect cover for an undercover surveillance team to get footage of chulpayev, we were told was involved in a huge criminal operation, a man with a well documented record of ruthless violence as a russian mafia boss in new york. >> beat up people, had terrorist mindset, threatening, extorting, kidnapping, torturing people. >> reporter: this lawyer came to know him well when he cross-examined him about his crimes. >> reporter: how bad was he? >> scale of one to ten, probably 100. young women, held captive, family held if they weren't prostitutes. >> reporter: he could be serving life in prison or deported to russia, but he