Hartmann is an agent of the D.E.O..
Hartmann removed the Hellgrammite's stinger from a guard's deceased body at Plastino Chemicals. Later at the D.E.O. base, Hartmann reported to Director Hank Henshaw and Agent Alex Danvers that they had discovered that the Hellgrammite's blood had a chlorine foundation instead of being carbon based like humans. After Agent Danvers deduced that the Hellgrammite was eating the chemicals, he then came to the conclusion that given the Hellgrammite's home planet's atmospheric conditions, DDT was the closest thing on Earth that the Hellgrammite could find to food.