This is the 3975th most frequent Arabic word.
بمقتل
"بمقتل" means "with the killing" or "in the death."
Here 'بمقتل' is used to indicate the cause of shock or impact (the killing of the journalist).
العالم أُصيب بصدمة بمقتل الصحفي.
The world was shocked by the journalist's killing.
In this sentence, 'بمقتل' signifies the event that confirmed the occurrence of the crime (the killing of a person).
تحقق الجريمة بمقتل شخص ليلاً.
The crime is confirmed by the killing of a person at night.
Finally, 'بمقتل' reflects the reason for the family's sorrow (the killing of one of their members).