Jaya Roy, superintendent of police in Ranchi, in the eastern state of Jharkhand, identified the suspect as Devesh Kumar, who was arrested in Dumka district.
â€œHe will be presented in court today [Tuesday] and then brought to Ranchi,â€ Roy told ucanews.com.
Cardinal Toppo, who serves as archbishop of Ranchi, received a letter last week demanding the payment of 50 million rupees (US$780,000) and threatening death if the amount was not paid.
The letter was sent in the name of the Peopleâ€™s Liberation Front of India (PLFI), a breakaway faction of the Communist Party of India (Maoist), though Roy said the suspect has no connection with the organization.
The suspect sent the letter to settle a personal score with a man identified only as Amit, the police official said.
â€œKumar mentioned Amitâ€™s name and telephone number in the letter so that Amit would face police investigation and arrest,â€ Roy told ucanews.com.
He added that police are investigating any other links the suspect might have to criminal activity.
Cardinal Toppo acknowledged receipt of the death threat last week but said he had no idea why Maoists would have had any cause to threaten him.