"Skyscraper of Death"
Superman Daily Newspaper Strip - April 3, 1939 to April 29, 1939
The Superman of yesteryear - grim, determined and unmoved by death. In this brief but fast-paced serial, Superman investigates a series of accidents plaguing the construction of the Atlas Building, uncovering sabotage on behalf of a rival builder.
His investigation racks up a serious body count - a night watchman-cum-saboteur succumbs to heart failure after being saved from what would have been a fatal plunge with only inches to spare (Superman - at this point in his career not yet able to fly - plummets alongside the doomed man, catching up to him and using some curious physics to reverse his terminal descent at the last possible moment).
Witnessing a man dying of stress doesn’t give the Man of Steel a moment’s pause in terrifying his next suspect into confession, although the crook survives - unlike his boss, who is fatally shot while fleeing a police officer, and the criminal mastermind of the affair whose misdeeds earn him a trip to the electric chair.
The early Superman doesn’t directly take lives, but he doesn’t stand in the way of the guilty getting their mortal comeuppance - even if they literally do so at his very feet.