He was able to prove an alibi which could not be shaken.
From the time that he left his brother's room he was never out of sight of some one or other.

So it could not be he who climbed over roofs and through trap-doors.

It's a very dark case, and my professional credit is at stake.

I should be very glad of a little assistance." "We all need help sometimes," said I.
"Your friend Mr.Sherlock Holmes is a wonderful man, sir," said he, in a husky and confidential voice.

"He's a man who is not to be beat.