Northern Sami language
While imprisoned at the Akershus Prison, Hætta started translating the Bible into the Northern Sami language, in cooperation with professor Jens Andreas Friis. After his release from prison in 1867, he joined Friis and Ludvig Kristensen Daa on a scientific excursion, married in 1868, settled in Guovdageaidnu, and continued his translation work. The translated "New Testament" was finished in 1869 and published in 1874. The translated complete Bible was printed in 1895. Hætta also contributed to the dictionary "", and translated other books into Sami language. Several of his wood sculptures from Sami tradition are now located at the Norsk Folkemuseum.