“Vladimir A. Pasechnik, first and foremost a scientist, was also a highly moral person, as was made clear after he defected to Great Britain in October 1989. The reasons for Pasechnik’s defection were multiple, complex, and conflicted. One of those reasons unquestionably included a moral component. Pasechnik had over time come to deplore the work that he was doing to formulate biological weapon agents, perfect means for their dispersion, and develop delivery systems for them. If not for his defection, the Soviet offensive biological warfare program, codenamed Ferment, might not have been disclosed between 1990 and 1992, which coincided with the last years of President Gorbachev’s tenure. The world owes Pasechnik its thanks for having made it more secure.”
There is his story as told by his son (на русском).