Los Angeles County police are reportedly probing whether it was jealousy or personal resentment that drove Huu Can Tran, 72, to allegedly massacre 11 people at a dance hall Saturday night, the Los Angeles Times reports, citing police sources. The report comes as investigators admit publicly that they’re unsure if they’ll ever pin down a motive for the grisly killings because Tran killed himself the following morning. While cops scramble to identify a motive, Tran’s former friend and tenant told the Times that he always was a “miserable and desperate” man who’s only reprieve was daily trips to the same dance studio he shot up on Saturday. Cops provided more insight into Tran’s potentially troubled personal life on Monday, saying investigators uncovered hundreds of ammunition rounds and materials to create homemade gun suppressors—also known as silencers—at his home.