Ankur Padia, who had been on the run since the kidnapping and murder of Rudraksh Handa early this month, was arrested from Kanpur, they said.
Confirming Ankur's arrest, Inspector General of Police (Kota) Ravi Prakesh Mehrada said an official announcement of his arrest would be made after his arrival in Kota.
Ankur's brother Anoop, who was wanted in a cheating case and had been on the run for seven years, was also arrested.
Refusing to reveal further details, Prakesh said legal proceedings against Ankur and his brother would be initiated only after their arrival in Kota tomorrow.
Following the incident, Rudraksh's parents had demanded a CBI probe into the matter while protests were held to demand immediate arrest of the culprits.
State government had sent DGP (Crime) Ajit Singh to camp in Kota to supervise the investigation in the case.