Really? By DHS you mean Homeland Security. Sounds pretty fishy to me.
DHS is a shipping company.
DHL is the shipping company.
Should have pulled a gun on him, forced him down to the ground and held him until the cops came, least thats what I would have done with his story he gave and the circumstances, cant be too careful, its 2014
Sounds good on paper. If he is legit or scared he will get on the ground, If not, he will attack you very quickly or run. If he lays on the ground or runs you don't shoot. If he attacks you, shoot. You have just escalated the situation into a 33.3% chance you will have to hire a lawyer.
I will and have took my chances on situations like this.