In March 1949, he was arrested by the regime's secret police, the Securitate. The latter discovered his name while investigating the Bucharest connections of the armed resistance movement. Late in 1948, Tonegaru had obtained a Belgian Red Cross parcel for Teohar Mihadaş, a poet and former member of the fascist Iron Guard, who, unbeknown to his benefactor, had passed it on to an anti-communist fighter in his native Bistriţa. Caught up in the subsequent Securitate clampdown, Mihadaș was tortured until he implicated his connections. According to one account, the Securitate officers storming into Tonegaru's house treated him like a ringleader, and, having misinterpreted a piece of paper on which the poet had sketched out a piece titled "Pistolul lui Werther" ("Werther's Gun"), pressed him to hand in his weapons, and repeatedly beat him with a crop.