Perhaps he strangled her first and then did the other things. Tragic but possible in his remorse and frustration at both her and him he may have continued to beat on the corpse. :'( (Not that I know anything.)
How horrifying and traumatic for the boy! Not only that time but all the times prior.
That is awful but when you multiply it by the thousands upon thousands around the world who are living similar things it is so tragic.
What if we spent half the amount of energy we do bad mouthing others and bemoaning our status and sent our thoughts and prayers to those who are in distress instead?
Prayers of healing for this boy and our world. In Jesus name, for Christ's sake, amen.