He tried to reason with the unknown criminal.

Through some process, this unknown criminal had managed to control the minds of unwitting men.

He was determined to come to closer grips with an unknown criminal.

The nun sometimes offered him profiles of unknown criminals in the early books.

An unknown criminal had made a vague-worded threat against Sutton.

This was the fake bottle left by an unknown criminal in place of the real master poison!

It increased his alibi, made him seem to be a prospective victim of an unknown criminal.

Yet the face in the picture is not that of the unknown criminal, but the most celebrated British artist of the 20th century.

Without any prospects for the future, unknown criminals are taking over power.

He played the role of a pretty school boy who gets attacked by an unknown criminal.