He retired to obscurity in Adelaide, leaving behind him still a slight, persistent mystery: why had he really delayed?

But the research, astronomers said, shows the power of "multi-wavelength astronomy" in investigating persistent mysteries.

One of the most persistent mysteries of human existence is why we fall in love.

The most persistent mystery remains the bomber's selection of targets, aside from their connections to advanced technology or their unpopularity among environmentalists.

There's a persistent mystery to the way flat patterns fold up into full ones.

Over the decades, the persistent mystery about who killed her husband has been frustrating, discouraging and disheartening, she said.

The case generated international media interest because of the persistent mystery of her killer's identity and the grisly circumstances surrounding her death.

It is one of the persistent mysteries of aging, researchers say.

This was arguably due to public fascination with a persistent mystery surrounding the lives of the two icons.

I am watching the opalescence of my absinthe, and it leads me to ponder upon a certain very curious mystery, persistent in legend.