Why didn't the Homunculi just kill Barry's body?

This is something that I just thought of, but seeing as a human soul cannot exist without a body and vice versa, why did the Homunculi even bother with releasing Barry's body to track Barry down after realizing he was working for Mustang?

They literally could have just killed/destroyed his body and eliminated Barry remotely without risking Barry's body leading Mustang's group back to the 3rd Lab, which ultimately resulted in Lust's death.