There is even evidence leading to the identity of this new mysterious killer.

That mysterious killer was worrying both of us, for nothing about it fitted in, anywhere.

In the meanwhile, various college girls get killed by a mysterious killer.

There was only the knowledge that a great, invisible, mysterious killer had been loosed on the world.

But could the mysterious killer back up his threats?

A private detective is pursued by both police and a mysterious killer.

He didn't worry much about mysterious killers coming to get him.

A police officer turned security chief must protect a handsome Hollywood star whose life has been threatened by a mysterious killer.

The police were attributing five slayings over the past week to the mysterious killer.

For a moment, she thought he was dead, yet another victim of the mysterious killer.