JUDGMENT & ORDER : Manojit Bhuyan, J. The appellant Nikumani Sarmah has been convicted for committing offence under Section 302 of the Indian Penal Code and sentenced to suffer rigorous imprisonment for life with fine and default stipulations. 2. The case on hand is in respect of causing death of his 15 month old nephew Bhargav Sarmah by means of a dao on 23.07.2008. According to the prosecution case, at around 3 P.M. of 23.07.2008, the appellant assaulted his nephew by means of a sharp weapon on his neck and caused death. The appellant also assaulted his neighbour Bapukan Sarma (PW-2) with an axe and attempted to kill him by causing grievous injury on the head, eye and back. Ejahar in the case was lodged by Rajendra Bordoloi (PW-5), who is a Priest and an eye witness to the incident. On the basis of the said ejahar, Kalaigaon P.S. Case No.112/2008 was registered against the appellant under Section 302/326/307 IPC. Investigation commenced, memos were drawn, statements of witnesses were recorded, the autopsy on the deceased was conducted and eventually charge sheet was filed against the appellant, committing the case to trial. Formal charges under Section 302/326/307 IPC were also drawn up by the Court and trial commenced. 3. As many as 14 (fourteen) witnesses were examined from the prosecution side, including the Medical Officer (PW-4), the Executive Magistrate (PW-12) who had conducted Inquest and the Investigating Officers (PW-13 & PW-14). The statement of the appellant under Section 313 CrPC was also recorded. 4. Rajendra Bordoloi (PW-5) presented himself as an eye witnesses to the incident of 23.07.2008. Referring to the testimony of Rajendra Bordoloi (PW-5), he stated that he was invited to recite the holy book at Makoni Devi’s house, who is PW-8 and mother of the appellant. A pot containing water was kept nearby and the appellant asked him to sprinkle water on him. Thereafter, the appellant went outside, brought his nephew on his lap, sat beside PW-5 and sawed the baby in the neck with a dao. The appellant then brought a glass and filled it with blood. Out of fear PW-5 went outside where he met Bapukan Sarma (PW-2) and told him what the appellant has done and also that he should not go there. The appellant then brought a glass and filled it with blood. Out of fear PW-5 went outside where he met Bapukan Sarma (PW-2) and told him what the appellant has done and also that he should not go there. When Bapukan Sarma started to go home, the chain of his cycle got loose and as he was trying to fix it, the appellant hacked him with an axe. PW-5 also stated that he had narrated the incident to the police, who also seized the axe and the dao. He also stated that he put his signature on the Seizure List (Ext.1) and that police also got his statement recorded by a Magistrate, which is Ext.4. In cross, PW-5 stated that the appellant is healthy and he had no knowledge about any mental ailments. He reiterated the statement of having seen the appellant assaulting Bapukan Sarma (PW-2). In his statement made under Section 164 CrPC, the narration of the incident was in line with the deposition made before the Court. PW-5, as the informant, had also narrated the incident without any discrepancy in the ejahar dated 25.07.2008. 5. The findings of the Court below that Bapukan Sarma (PW-2) is also an eye witness, the same is not accepted having regard to his testimony, which do not indicate that he was a witness to the incident. Although he presented himself as an injured witness, there are no medical reports brought on record supporting the injuries sustained by him. It thus appear that Rajendra Bordoloi (PW-5) alone stood as a direct witness. 6. The homicidal death of the 15 month old baby as a result of injuries caused by a sharp weapon is not in dispute. The medical evidence in the form of the Post Mortem Report (Ext.2), duly proved by Dr. Mandeep Roy Deka (PW-4), being the medical expert who had conducted autopsy on the dead body, corroborates the cause of death. The homicidal death of the 15 month old baby as a result of injuries caused by a sharp weapon is not in dispute. The medical evidence in the form of the Post Mortem Report (Ext.2), duly proved by Dr. Mandeep Roy Deka (PW-4), being the medical expert who had conducted autopsy on the dead body, corroborates the cause of death. The seizure of the sharp cutting weapon i.e. dao has also been brought on record through the Seizure List (Ext.1) and through the deposition of Puran Kalita (PW-3), Rajendra Bordoloi (PW-5), Sisu Ram Nath (PW-9) and by Amulya Deka (PW-14), who was working as the Officer-in-Charge of Kalaigaon Police Station on the date of the incident and who deposed that the dao and the axe were recovered from the back side of the appellant’s house, concealed under some thatch and bamboo. 7. The fact that Rajendra Bordoloi (PW-5) was invited to the house of the appellant to recite the holy book on the occasion of “Shraddh” ceremony of the appellant’s father on the date of occurrence, finds support from the testimony of Binoy Sarma (PW-6), who is the elder brother of the appellant and Sabita Sarma (PW-7), who is the elder sister of the appellant. The deposition of Rajendra Bordoloi (PW-5) as the sole eye witness to the incident have remained consistent and unshaken from the time when he had filed the ejaher, followed by his statement under Section 164 CrPC and that of his testimony before the Court. His evidence as to the involvement of the appellant could not be demolished in cross-examination. To this extent, the prosecution has successfully proved the guilt of the appellant beyond all reasonable doubt. 8. One important aspect brought on record by Binoy Sarma (PW-6), who is the elder brother of the appellant; Smti. Makoni Devi (PW-8), who is the mother of the appellant and statement made by the appellant under Section 313 CrPC, relates to the mental illness of the appellant. PW-6 stated in cross that the appellant is a mentally ill person who was undergoing treatment at Tezpur Mental Hospital. PW-8 also stated in cross that on the date of occurrence, a puja ceremony was also held to cure her son i.e. the appellant of his mental illness and that her son had been undergoing treatment under one Dr. Jayanta Das at Guwahati. PW-8 also stated in cross that on the date of occurrence, a puja ceremony was also held to cure her son i.e. the appellant of his mental illness and that her son had been undergoing treatment under one Dr. Jayanta Das at Guwahati. In the statement under Section 313 CrPC, the appellant also stated that he is a mentally retarded person and he did not know how the incident had taken place. 9. As evidence has been brought on record on the plea of insanity, thereby seeking protection under Section 84 of the Indian Penal Code, it will be useful to reproduce the said provisions as under: “84. Act of a person of unsound mind.- Nothing is an offence which is done by a person who, at the time of doing it, by reason of unsoundness of mind, is incapable of knowing the nature of the act, or that he is doing what is either wrong or contrary to law.” The aforesaid provision makes it clear that insanity or unsoundness of mind belong to the stages when a person is incapable of knowing the nature of the act or unable to understand what is right or wrong and that stage must relate to the period when the offence had been committed. In this respect, it will also be useful to refer to and reproduce the provisions under Section 105 of the Evidence Act, 1877, which reds as under: “105. Burden of proving that case of accused comes within exceptions.- When a person is accused of any offence, the burden of providing the existence of circumstances bringing the case within any of the General Exceptions in the Indian Penal Code, (45 of 1860), or within any special exception or proviso contained in any other part of the same Code, or in any law defining the offence, is upon him, and the Court shall presume the absence of such circumstances.” Ordinarily, the burden of proving an offence always lies on the prosecution and never shifts. However, the existence of circumstances for bringing a case within the exception of Section 84 IPC lies on the accused. 10. No evidence is brought on record to support the plea of insanity that at the time of commission of the offence, the appellant was of unsound mind or was incapable of knowing the nature of the act, as to whether it was right or wrong. 10. No evidence is brought on record to support the plea of insanity that at the time of commission of the offence, the appellant was of unsound mind or was incapable of knowing the nature of the act, as to whether it was right or wrong. Although PW-6 stated that the appellant was undergoing treatment at Tezpur Mental Hospital, no material was brought on record in support of the same. In the same breath, the statement of PW-8 that her son i.e. the appellant had been undergoing treatment under one Dr. Jayanta Das at Guwahati, is only a bald statement shorn of any evidence in support. During the entire proceedings the appellant has nowhere stated with supporting materials that he was insane during any period prior to or on the date of the incident. He only stated that he was a mentally retarded person. To reiterate, no evidence was brought on record to demonstrate that the appellant was suffering from unsoundness of mind and/or that his cognitive faculties was so impaired that at the time and date of the incident he was unaware of the nature of the act. 11. The law relating to plea of insanity have received due consideration of the Apex Court with reference to Modi’s Medical Jurisprudence and Toxicology. Reliance is placed in the case of Shrikant Anandrao Bhosale v. State of Maharashtra, reported in (2002) 10 SCC 784; Sudhakaran v. State of Kerala, reported in (2010) 10 SCC 582 and in the case of Mariappan v. State of Tamilnadu, reported in (2013) 12 SCC 270 . In the said cases it has been categorically held that although a person may be treated medically as a mentally sick person, however, for the purposes of claiming the benefit of the defence of insanity in law, he would have to prove that his cognitive faculties were so impaired at the time when the crime was committed, as not to know the nature of the act. The settled proposition of law as to the crucial point of time for ascertaining the existence of circumstances within the purview of Section 84 IPC has been consistently held as the time when the offence is committed. Also, it is well settled in law that when a person is bound to prove the existence of any fact, the burden of proof lies on that person. 12. Also, it is well settled in law that when a person is bound to prove the existence of any fact, the burden of proof lies on that person. 12. In the instant case, there is no material brought on record that the appellant was suffering from mental illness during any period prior to and/or on the date of the incident. It leaves no manner of doubt to hold that the appellant was not insane when the crime took place. The benefit of Section 84 IPC, therefore, cannot be extended to the appellant. 13. In the light of the above discussions, and having regard to the settled proposition of law, we fully agree with the conclusion arrived at by the trial Court. The conviction and sentence of the appellant stands affirmed and the present appeal stands dismissed.