Editing Andrei Chikatilo (section)

==Surveillance and second arrest==
Police placed Chikatilo under surveillance on 14 November. In several instances, particularly on trains or buses, he was observed approaching lone young women or children and engaging them in conversation. If the woman or child broke off the conversation, Chikatilo would wait a few minutes and then seek another conversation partner.{{sfn|Conradi|1992|p=192}} On 20 November, after six days of surveillance, Chikatilo left his house with a large jar, which he had filled with beer at a small kiosk in a local park{{sfn|Cullen|1994|p=175}} before he wandered around Novocherkassk, attempting to make contact with children he met on his way.<ref name="330 page"/> Upon exiting a cafe, Chikatilo was arrested by four plainclothes police officers. He offered no resistance as he was handcuffed and placed inside an unmarked police car.{{sfn|Conradi|1992|p=193}}

Upon his arrest, Chikatilo gave a statement claiming that the police were mistaken and complained that he had also been arrested in 1984 for the same series of murders.{{sfn|Cullen|1994|p=181}} A strip-search of the suspect revealed a further piece of evidence: one of Chikatilo's fingers had a deep flesh wound he had self-treated with [[Iodine (medical use)|iodine]]. Medical examiners concluded the wound was from a human bite. Chikatilo's penultimate victim, Viktor Tishchenko, was a physically strong youth. At the crime scene, the police found numerous signs of a ferocious physical struggle between the victim and his murderer. Although a finger bone was later found to be broken and his fingernail had been bitten off, Chikatilo had never sought medical treatment for this injury.{{sfn|Cullen|1994|p=177}}

A search of Chikatilo's belongings revealed he was in possession of a folding knife and two lengths of rope. A sample of his blood was taken,{{sfn|Conradi|1992|p=198}} and he was placed in a cell inside the KGB headquarters in Rostov with a [[Informant|police informer]], who was instructed to engage Chikatilo in conversation and elicit any information he could from him.{{sfn|Cullen|1994|p=179}} The next day, 21 November, formal questioning of Chikatilo began. The interrogation was performed by Issa Kostoyev. The strategy chosen by the police to elicit a confession was to lead Chikatilo to believe that he was a very sick individual in need of medical help. The intention was to give Chikatilo hope that if he confessed, he would not be prosecuted by [[insanity plea|reason of insanity]]. Police knew their case against Chikatilo was largely [[circumstantial evidence|circumstantial]], and under Soviet law, they had ten days in which they could legally hold a suspect before either charging or releasing him.{{sfn|Berry-Dee|2011|p=308}}

===Blood group analysis===
On 21 November, the results of Chikatilo's blood test again revealed his blood type to be type A and not type AB. Due to the amount of physical and circumstantial evidence investigators had thus far compiled, which indicated Chikatilo was indeed the murderer they had been pursuing, plus the fact that investigators had deduced the blood type of the murderer they had pursued using semen samples obtained from the clothing and bodies of fourteen of the victims as opposed to actual blood samples, investigators obtained a sample of Chikatilo's semen to test his blood type, the results of which confirmed that Chikatilo's semen was type AB, whereas his blood and saliva were type A.{{sfn|Cullen|1994|p=190}}{{refn|group=n|Investigators had received a circular in 1988 indicating that in extremely rare cases, a man's blood type may differ from his semen and saliva type. A [[serology]] expert would later state at Chikatilo's trial he was an example of this "extremely rare phenomenon" she termed "paradoxical secretion."{{sfn|Cullen|1994|pp=149–150}} These findings have been openly dismissed by experts in serology and [[DNA profiling|DNA analysis]], who state that paradoxical secretion is an impossibility.<ref>{{Cite web|url=https://forensicdna.com/wp-content/uploads/2020/02/1stq07a.pdf|title=Proceedings of the California Association of Criminalists: Fall 2016 Seminar|publisher=The CAC News|date=1 February 2017|access-date=14 June 2023|page=21}}</ref>}}

Throughout the questioning, Chikatilo repeatedly denied that he had committed the murders, although he did confess to molesting several of his pupils during his career as a teacher.{{sfn|Cullen|1994|pp=187–188}} He also produced several written essays for Kostoyev which, although evasive regarding the actual murders, did reveal psychological symptoms consistent with those predicted by Dr. Bukhanovsky in the 1985 profile he had written for the investigators.<ref>{{cite news|last=Matthews|first=Owen|url=https://www.themoscowtimes.com/1999/01/30/a-killers-confidante-in-a-murderous-town-a280832|title=A Killer's Confidante In a Murderous Town|work=[[The Moscow Times]]|date=30 January 1999|access-date=6 November 2022}}</ref> The interrogation tactics used by Kostoyev may also have caused Chikatilo to become defensive; the informer sharing a KGB cell with the suspect reported to police that Chikatilo had informed him that Kostoyev had repeatedly asked him direct questions regarding the mutilations inflicted upon the victims.{{sfn|Cullen|1994|p=190}}