From 1948 to 1954 he served the sentence in the Viatlag prison camp, Lesnoy, Kirov Oblast in Northern Russia.

Mandri was released in 1954 and returned to Estonia, where the Soviet authorities forbade him to get closer than 101 km to Tallinn under the 101st kilometre rule.

In 1956 Mandri wrote a personal letter to the Chairman of the Presidium of the Supreme Soviet Kliment Voroshilov, after which he got his sentence retroactively shortened to five years allowing him to enter Tallinn again.

In Soviet films, Heino Mandri was usually cast as characters who were officers of the Wehrmacht, German businessmen, or American spies.

Heino Mandri was acquitted of all political charges and fully rehabilitated in his rights only shortly before his death in 1990.