Fatwas of Ibn Baz
83- The ruling on using superstition to find lost objects
Q: Is it permissible when someone loses something or a person is killed to go to Al-Mulawwith or Al-Mulahhis who asks the accused to lick a heated metal bar, claiming that tongue of a lying person will be burnt while that of a truthful person will not. Is it permissible to use this method to detect criminals compared to the use police dogs to identify criminals?
A: Undoubtedly, this act is Batil (null and void) and Munkar (unacceptable or disapproved of by Islamic law and Muslims of sound intellect). It is a way to burn the tongues and cause harm to Muslims. It has no basis in Shari`ah (Islamic Law) as far as we know. Rather, it is superstitious and an act of charlatans who want to consume people's wealth unlawfully. It is thus prohibited, and is in no way comparable to the use of police dogs.
(Part No. 28; Page No. 350)
If a person loses something, they may follow the tracking methods used by the Arabs and approved by the Shari`ah to find lost objects, runaway slaves or the like. As for murders in which criminals are unknown, an investigation should be run to identify them, asking those having information about the related crimes, those surrounding the crime scenes and so on and so forth. As for the use of heated bars that are applied to the tongues of suspects, such method is not permissible because it is invalid and baseless. It is never analogous to the use of police dogs, because dogs have the powerful identify criminals through smell.
Source: Chapter on Sihr