Thames Valley Police has launched a murder investigation after an incident in Aylesbury in the early hours of Thursday morning.
Police were called to a residential address in Harcourt Green just before 1am, following an altercation between two men that ended in a serious assault.
53-year-old Mark Austin of Coxhill Way, Aylesbury died yesterday at Stoke Mandeville Hospital.
A 49-year-old man who was arrested shortly after the incident on suspicion of GBH has since been sectioned under the Mental Health Act.
The murder investigation is at a very early stage, however the victim and the suspect knew each other and this was not a random attack.
Anyone with any information regarding this incident should contact the Major Crime Incident Room at Taplow via the non-emergency number, 101.
If you don't want to speak directly to the police you can contact the independent charity Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org.
No personal details are taken, information is not traced or recorded and you will not go to court.