Both were arrested on 1 February 1944 in Via Giulia, where they packed hand grenades in the group's magazine, and were immediately taken to via Tasso. Mattei, professor of chemistry at Milan Polytechnic, hanged himself with his braces on 4 February for fear of revealing the names of his fellow fighters under torture. Labò, a student of architecture and an intellectual, ferociously tortured and detained for a long time in inhumane conditions, put the blame on himself, to save Mattei, as the sole person responsible for the Via Giulia magazine. He was shot on March 7 with nine other partisans.