Yes, they’ve been discredited as a binary, true or false, lie detector. However a skilled investigator can still use polygraphs as one tool in a toolbox to hone

Yes, they’ve been discredited as a binary, true or false, lie detector. However a skilled investigator can still use polygraphs as one tool in a toolbox to hone in on particular areas. They can then either have the subject contradict themselves or find areas to further investigate (e.g. asking the neighbors what sorts of people the subject has over.)