It's a form of delusional misidentification syndrome
, or DMS, where the patient believes they're being persecuted by someone who disguises himself as other people.
They argued Kot suffered from paranoia and other acute symptoms associated with Capgras delusion, a misidentification syndrome
common in patients diagnosed with schizophrenia.
Delusional misidentification syndrome
includes a group of disorders that present delusions about oneself, others, places and objects.
Hoffmann, "Isolated Right Temporal Lobe Stroke Patients Present with Geschwind Gastaut Syndrome, Frontal Network Syndrome and Delusional Misidentification Syndromes
," Behavioral Neurology 20:3 (2008), 83-9.