Science-Fiction book set in the future about a detective investigating a series of murders

It takes place in a futuristic human society. I think some humans (maybe the detective) have psychic abilities that let them read emotions or general thoughts of others. I remember the cause of the murders was some kind of alien metal that made people violent. One of the suspects used garden shears made of the metal and I think another used a ray gun. I read it in the early 2000’s but I think it may have been written in the 80’s.