Which Serial Killer is Different?

[Fishface]

Dean Corll, an electrician; Des Nilsen, a civil servant; Mark Smith, who sells his paintings; Eddie Leonski, a secretary; Jeff Dahmer, a factory worker; Eric Armstrong, who gassed up the passenger jets at an airport; and Patrick Kearney, an engineer, all have one other major career item in common in their resumes. Which one of these guys is different from the others, and how?

[Shelley]

All but Eric Armstrong served in the Army. Armstrong served in the Navy.

OR

All but Des Nilsen served in the United States Department of Defense. Nilsen is British.

[Fishface]

Closer than heck, but...BZZT!

[Shelley]

Dean Corll is the only one who, having worked as an electrician, did something similar to what they did while serving?

[Shelley]

I also looked at whether they killed while they were in service. Four did and two didn't. That can't be the answer. Right?

Dean is the only one who didn't serve in a foreign country. Maybe that's it. Eric was technically on a ship but did go to foreign ports.

[Fishface]

BZZT!

[Shelley]

Dahmer was found unsuitable for service (but did get a honorable discharge). The others weren't found unsuitable.

[Shelley]

Dahmer is also the only one to kill before serving.

[Fishface]

Shelley wrote: "Dahmer was found unsuitable for service (but did get a honorable discharge). The others weren't found unsuitable."

DING DING DING! Correct! Jeff was kicked out for refusing to get treatment for his alcohol problem. The others fulfilled their commitments and were ultimately honorably discharged, except for Eddie who was in the Army until they hanged him for murder. He is still in a military cemetery, in fact.

[Shelley]

[Lady ♥ Belleza, Gif Princesa]