During Soviet rule of Estonia, Aleksei Dressen worked as a policeman in the Soviet militia. In 1993 he started working for the reestablished Estonian Security Police. In 1994 he lost his police ID. A year later there was a disciplinary charge for wrongful conduct at work. This happened several times during his career. In 1999 his salary was cut by 30% for two months.[3]
Despite all this Aleksei Dressen managed to become a director of several different units in the Estonian Security Police.[4]
Aleksei Dressen and his wife Viktoria were arrested on the morning of 22 February 2012 at Tallinn Airport. Viktoria was about to board a flight to Moscow. During the arrest a thumb drive full of information was seized.[4] The chief architect behind Dressen's capture is considered to be the deputy chief of the Estonian Security Police Aleksander Toots. In 2012 Dressen was sentenced to 16 years in prison.[5]
On 26 September 2015, he was handed over to Russia in exchange for Eston Kohver.[6][7] The prisoners were exchanged in a manner reminiscent of Cold War spy exchanges, on a bridge over the Piusa River.