Descibe the relationship between the neighbour Mrs. Alexander and Christopher?

Mrs. Alexander is Christopher's neighbor. Up until he interviews her about Wellington's death, they don't know each other.

I went up to Mrs. Alexander and said, "Do you know anything about Wellington being killed?"

Then she turned the electric hedge trimmer off and said, "I'm afraid you're going to have to say that again. I'm a little deaf."

So I said, "Do you know anything about Wellington being killed?"

And she said, "I heard about it yesterday. Dreadful. Dreadful."

I said, "Do you know who killed him?"

And she said, "No, I don't."

I replied, "Somebody must know because the person who killed Wellington knows that they killed Wellington. Unless they were a mad person and didn't know what they were doing. Or unless they had amnesia."

And she said, "Well, I suppose you're probably right."

I said, "Thank you for helping me with my investigation."

And she said, "You're Christopher, aren't you."