I've played the game a bit further and found a small kind of bug. When I killed Lt. Gareth he died from bleeding, after that I killed a remaining medic but Gareth was still there but invisible and only died if I shot him again. This isn't gamebreaking or anything but though I should let you know.
Thanks for reporting it! That's a known bug (it happens when the medics are still alive so they accidentally heal the lieutenant even though he's supposed to be unconscious). We're working on a fix, and it should be included in our next update.