An activist who installed a memorial plaque on the derelict home of a victim of Soviet repression has been found guilty of damaging a cultural heritage site in Arkhangelsk in northern Russia, the Interfax news agency reports.

Dmitry Kozlov, a member of the “Last Address” group, which commemorates gulag victims by installing small plaques on their homes, has been ordered to pay a fine of 15,000 rubles ($250), his lawyer Ivan Pavlov told Interfax.

“It is the minimum punishment for this charge but we consider the decision to be unlawful and unfounded and will appeal,” Pavlov was cited as saying.

It is the first time an activist from the group has been prosecuted, “Last Address” co-founder Sergei Parkhomenko said earlier.