Some just don't understand.
They default to why wasn't this or that killing investigate. When you all agree they were killed by terrorist then what is there to investigate?
This case is clear, everyone agrees she was killed by Israeli soldiers.
For the other cases, investigate who trained the terrorists, who funded them, etc.
You keep saying there's no harm in investigating, that's not true. For the FBI to come after the Israeli investigation and do their own one is to say, "we don't trust you." That's a slap in the face, and that's why it's not done for any other ally.
Besides Israel.
Do you see the problem?