Giustino Sebastiano Pasquale de Jacobis was born on 9 October 1800 at San Fele in the Province of Potenza.

[2] In 1839, he was appointed as the first Prefect Apostolic of Ethiopia and entrusted with the foundation of Catholic missions there, a jurisdiction that included what is now Eritrea.

After laboring with great success in Ethiopia for almost a decade he was appointed as the Titular Bishop of Nilopolis in 1847 and not long afterwards the Vicar Apostolic.

His missionary efforts aroused opposition on the part of Ethiopian Orthodox Patriarch Abuna Salama III and Emperor Tewodros II which resulted in imprisonment and exile.

[1] He died of fever in 1860 at Hebo of what is now the Southern Administrative Region of Eritrea, while en route to Halai, where he hoped to regain his health.

Jacobis was declared to be Venerable on 28 July 1935 after Pope Pius XI acknowledged the late bishop's life of heroic virtue.