The problem is that liberals and Democrats live in a parallel world that is not based in reality. Ask one of them the following question: If your daughter was kidnapped by two men and one was caught, would you really care what was done to the one who was caught if it helped to find your daughter?
There was a case similar to that in Boston 30 years ago. Guy killed a girl. Group of guys kidnapped him, tortured him til he showed them the shallow grave.
They couldn't prosecute him because of that illegal information-gathering method.