Who made it, how, and why are still unsolved mysteries.

Now, we have a greater understanding, but there are still unsolved mysteries of the mind.

Perhaps the biggest unsolved mystery that the authors might know something about is what happened this past summer.

What happened to this piece is still an unsolved mystery.

There are still many gaps in knowledge, and unsolved mysteries.

Since then there has been much speculation about her death, but it remains an unsolved mystery.

However, the identity of the mother is an unsolved mystery.

His investigation further leads him to an unsolved mystery 20 years ago.

Another mystery that would remain unsolved, at least for now.

However the case still has been considered an unsolved mystery.