"Poor fellow! Has this awful thing driven him ..." Tarling nodded.
"He was taken to the County Asylum this morning.

He had a fit in my office, and when he recovered he seemed to have lost his mind completely.
Now, Miss Rider, you're going to be frank with me, aren't you ?" She looked at him again and smiled sadly.
"I'm afraid I shan't be any more frank than I have been, Mr.Tarling," she said.

"If you want me to tell you why I assumed the name of Stevens, or why I ran away from London, I cannot tell you.

I had a good reason----" she paused, "and I may yet have a better reason for running away...." She nearly said "again" but checked the word.
He laid his hand on hers.
"When I told you of this murder," he said earnestly, "I knew by your surprise and agitation that you were innocent.

Later the doctor was able to prove an alibi which cannot be shaken.