Two Indonesian brothers have been arrested for allegedly murdering their 16-year-old sister over accusations of extramarital sex, police says the act could them executed if convicted.

The brothers who are aged 20 and 30, admitted that they attacked their sister with a log and a machete for having sex outside marriage, the killing was said by authorities to have taken place in Sulawesi Island’s Bantaeng regency.

The girls family also held the distant relative hostage for having relations with the girl after he refused to marry her.

The teen’s killing may have been linked to local norms focused on protecting family dignity, says Amnesty International Indonesia’s executive director Usman Hamid