[2][3] After ordination he taught and then became vice-rector of the Immaculate Conception Seminary and parochial vicar and administrator of the St Anne’s Parish in Ibeku from 1984 to 1986.

[2] Beginning in 1986 he studied at the Pontifical Biblical Institute in Rome, the Hebrew University in Jerusalem and the Philosophisch-Theologische Hochschule, Sankt Georgen, in Frankfurt, Germany.

[7][8] He speaks a number of languages including English, Italian, German, French, Spanish, in addition to Arabic.

[14] During his last month in this position, he addressed the Human Rights Council on the deprivation of human rights in Nicaragua, noting "the reported closure of several independent media outlets and non-governmental organizations, including faith-based organizations, and the allegations of the systematic use of violence by law enforcement in a climate of general impunity".

[15] On 23 December 2021, following his Christmas address to senior members of the Roman Curia, Pope Francis gave each attendee three books he recommended, including Nwachukwu's recent work on gossip, The Abused Word.