One of the three is understood to have been involved in previous violent robberies.
Funeral arrangements for Fr Roche, 68, a native of Athea, were finalised yesterday.
His remains will arrive at Dublin airport on Saturday and will be accompanied by fellow Kiltegan missionary and life-long friend, Fr Paddy Hyland. His nephew Jer Cunningham, who works with Irish Aid in Zambia, will also be on the flight.
The remains of Fr Roche will lay in repose at his sister Nora Cunningham’s residence at Glin Road, Athea, on Saturday from 5.30pm to 9pm.
Sympathy offered at St Bartholomew’s parish church, Athea, from 1pm on Sunday followed by Mass at 2pm.
Burial will take place at the Holy Cross cemetery in Athea.
Fr Liam Blayney, who was a classmate of Fr Roche’s at the St Patrick’s Missionary Society in Kiltegan, will be the chief celebrant at the Mass.
Anne Cunningham, a niece of Fr Roche, said the Department of Foreign Affairs had been extremely helpful.
A Mass will be offered in Kenya before the remains of Fr Roche are flown back to Ireland.
Fr Roche was one of a family of 11. His sisters, Kit, Mary Ann and Eileen, and brother Christy, who all live in Chicago, are travelling home for the funeral. Over the years, they fundraised in the US for Fr Roche’s mission.