Visitors to Munich’s Pinakothek der Moderne come for modernist treasures by Pablo Picasso, Franz Marc, Oskar Schlemmer, and the like. But this month, some visitors got to see something else they didn’t expect: the work of a museum employee, apparently hung without permission on the walls alongside masterpieces of the 20th century.

The German outlet Süddeutsche Zeitung reported news of the guerrilla presentation on Monday, noting that the police are now investigating the incident. Per the police, the artist was a 51-year-old employee in the technical services department; he’d allegedly hoped that showing his work in the museum would lead to future opportunities.

Details of his stunt remain unclear. Süddeutsche Zeitung reported that not even the museum administration is sure how long the work hung on the wall. “The supervisors notice something like this immediately,” a museum spokesperson told the publication.

The employee being investigated is not likely to face any major charges. The only criminal offense he could face is a minor infraction for drilling two holes into what had been a bare wall.

Still, according to Süddeutsche Zeitung, the worker’s employment status has changed: he was let go and banned from reentering the Pinakothek der Moderne.