Hi, while you're waiting, check out some earlier answers:
/u/TheFairyGuineaPig on historical usage of the firing squad versus other methods of execution
/u/Elphinstone quotes additional/alternative reasons in a thread in Short Answers to Simple Questions | February 21, 2018
/u/shmag discusses justification in the USA in When they executed people by firing squad why did they use several men from a distance to shoot?