The murder of Staines and his two boys, burned to death Jan. 23, 1999 as they slept in their jeep after a Bible study, attracted worldwide attention.
Shortly after the murder, police identified Hindu militant Dara Singh as the main suspect in the case. Despite an intense manhunt and a $23,250 reward, Hindu villagers in the eastern state of Orissa successfully hid Singh over the past year.
Singh has been wanted in connection with several criminal cases and has been on the run since allegedly leading the mob that attacked Staines. He was arrested with two of his sons as he sought to buy a gun, according to news reports.
The attack on Staines, a Baptist missionary who had worked with leprosy patients in India since 1965, came amid increased friction between militant Hindus and Christians. Some Hindu leaders have accused Christians in India of engaging in forced conversions.
Christians vehemently deny the charge.
Staines' widow, Gloria, said shortly after the killing that she forgave the killers. Nevertheless, she expressed pleasure Tuesday that Singh had been arrested so "he will not be able to kill others."
"Hundreds of thousands of people all over India, irrespective of caste, creed, have said Dara's action was not Hinduism and that they were ashamed of the deed," she told Reuters Tuesday.
While Christians welcomed the arrest, they also expressed concern about a recent order on conversion issued by the Orissa state government.
The order mandates a police inquiry before anyone adopts a new faith in the state.
"The notice has been served only to Christians," Isaac Puthensngany, a priest in the Catholic diocese where Staines was killed, told Reuters.
"Conversion from Christianity is not taken into consideration by these people."