The most credible theories are that Raetic was:

If these were credible theories, this country would have more serial killers than lawyers.

Over the years, a few credible theories have emerged from those familiar with the project.

A credible theory uniting all the evidence has yet to be formulated.

We don't have a credible unified theory of physics yet.

However, there is no consensus nor credible theory on who these people were.

One of the less credible theories that circulated at the time was reported by Harry Pusey.

According to a report in the Skeptical Inquirer in 1997 no credible theory of psi has yet been presented.

And none of them had posited a more credible theory than those put forth by Geordi.

There's no clear-cut evidence that the recipes featured on food shows are urging viewers to eat unhealthily, but it's a credible theory.