LEXINGTON, S.C. — The small sign posted above the doorway of the mobile home seemed starkly at odds with the collection of toys a few feet away: “Is there life after death? Trespass here and find out.”

The terse warning and an accompanying illustration of a handgun hung on the home of Timothy R. Jones Jr., 32, who was expected to face murder charges after his five children were found dead on Tuesday in a rural patch of the Alabama Black Belt. About 400 miles from the scene near Camden, Ala., state officials and neighbors here were grappling on Wednesday with whether they had missed conspicuous signals of imminent family violence.

And Mr. Jones himself emerged as a tragically paradoxical figure: an engineer, once described by a family therapist as “a highly intelligent, responsible father,” who endured an especially bitter divorce and now stands accused of killing his five children and abandoning their bodies, all wrapped in garbage bags. He was arrested hours after he left Alabama, when the authorities stopped his Cadillac Escalade at a checkpoint in Mississippi and found blood and materials to produce methamphetamine.

Days later, the authorities said, he led them to the barren ground, surrounded by tree limbs and red clay, where the bodies of the children rested. The eldest was 8 years old.