On Betazed in the mid-20th century, a small secret society was formed. The members of which strove to develop their telepathic skills in various ways. The abilities they managed to bring forth ranged from the amplification and projection of intense emotions into the mind of another, to telekinesis. Four hundred years later, psychopathic government researcher, Hent Tevren, discovered the classified data and taught himself the same skills that the psionic cult had developed. He was imprisoned at Jarkana after he'd killed his parents, amongst other people. (TNG novel: The Battle of Betazed)