I think the husband did it. He was only 70+ miles out of town -- that's not so far that he couldn't have killed her and gone back to LaGrange, with no one the wiser. So what if the insurance he would have gotten was small -- people don't need monetary reasons to kill, after all.
However, the death of the second woman makes it look like organised crime was involved:
Ponder [investigating officer] thought the similarities in the Little and Shields cases were mere coincidence. On his recommendation, the FBI stayed out of the second investigation.
Most of the police who worked the homicide disagreed with his assessment. To this day, Melvin Banks, East Point's chief detective on the case, believes that someone implicated in the internal investigation at C&S was responsible for Shields' death. "They're connected, no question," he says.
But East Point was never able to make an arrest. As with Little's, the case file is nowhere to be found.
Is there a hint there of police corruption? I found the statement by the second victim that she was acting undercover to help in the investigation significant. The scarf shoved down her throat, and the lack of robbery of her car and jewellery, makes it look like a calculated gesture of "silencing" someone.