Why would they kill me? I heard the Messenger of Allah ﷺ say: ʿIt is not permissible (to shed) the blood of a Muslim except in three cases: If a man disbelieves after becoming Muslim, or commits zina after being married or kills someone and is executed in retaliation.ʿ (Using translation from Aḥmad 509)   

سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ لَا يَحِلُّ دَمُ امْرِئٍ مُسْلِمٍ إِلَّا بِإِحْدَى ثَلَاثٍ بِكُفْرٍ بَعْدَ إِيمَانٍ أَوْ بِزِنًى بَعْدَ إِحْصَانٍ أَوْ يَقْتُلُ نَفْسًا بِغَيْرِ نَفْسٍ فَيُقْتَلُ  

The blood of a Muslim man who testifies that there is no god but Allah and that I am the Messenger of Allah should not be lawfully shed but only for one of three reasons: married fornicator, soul for soul, and one who deserts his religion separating himself from the community. (Using translation from Abū Dāʾūd 4352)  

قَالَ رَسُولُ اللَّهِ ﷺ لَا يَحِلُّ دَمُ رَجُلٍ يَشْهَدُ أَنْ لَا إِلَهَ إِلَّا اللَّهُ وَأَنِّي رَسُولُ اللَّهِ إِلَّا أَحَدَ ثَلَاثَةِ نَفَرٍ النَّفْسُ بِالنَّفْسِ وَالثَّيِّبُ الزَّانِي وَالتَّارِكُ لِدِينِهِ الْمُفَارِقُ لِلْجَمَاعَةِ