Amar Nath was arrested on Thursday night from his house in the slums of Jaitpur.
Amar Nath, who is originally from Maharashtra, lured the 11-year-old boy on February 28 while he was playing outside his school. He took the boy to an isolated place near a canal in Jaitpur and tried to sexually assault him.
As the boy resisted and threatened to reveal his crime, Amar Nath slit his throat and threw the body into the canal, Deputy Commissioner of Police Chinmoy Biswal said.
"During investigation, the boy's classmate said he had last seen him with a man wearing an earring, who was later identified as Amar Nath," the officer said.
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.