Actually, children have been disappearing in large numbers for centuries all over the world, and most of these cases have remained unsolved.

He suspected this murder, like so many others, would remained unsolved.

The case has remained unsolved to this day.

"A problem is not necessarily unsolvable because it has remained unsolved."

Despite the apparent simplicity of the action needed, the crimes had remained unsolved for too long, Jane thought.

Many of the major issues confronting government and nation remained unsolved, or at best marginally confronted in the 1977-8 period.

Commission Members have come and gone, but this problem has always remained unsolved.

The problem itself has occupied leading scientists for decades while still remaining unsolved.

His insights often proved beneficial in closing cases that otherwise may have remained unsolved.

Without his confession, these murders would have remained unlinked and unsolved.