As the US and Turkey are strengthening communication with Saudi Arabia, the tension over missing journalist Jamal Khashoggi, reportedly killed inside the consulate, is expected to abate.
I think there should be a "was" before "killed". I searhed "killed". There are many news titles just with "killed", such as,
9 killed and 21 injured ...
I think the titles use a such short term due to the lack of space (for a full sentence.)