Police said the accused Shankar, 30, a casual labourer in a textile unit from Madurai had executed all the three murders in a similar fashion by smashing the head of the victim with a huge stone while they were asleep.
In all, the accused did not have any major motive and the murders happened following petty quarrels under the influence of alcohol. The victims were all known to him and were staying with him.
Police, who were on a search for Shankar in connection with the murder of his roommate Isakkimuthu, 27, a textile firm worker and hailing from Thoothukudi on November 2, came to know that the accused is in prison.
He was lodged in prison on November 12 for murdering one Anbarasan along with his friend by smashing the head with a stone following a drunken brawl.
The police took him into custody and during inquiries Shankar confessed to have killed Isakki and hid his body in a cement water tank.
This murder came to light after the body began to decompose and a foul smell started to emanate from the tank.
The accused had executed both the murders in a similar fashion of smashing their heads within a fortnight while being out on bail in connection with another murder committed by him in 2018.
Police then produced him in court and was remanded in judicial custody.