"It looks like Gretchen finally met her secret admirer. She obviously said or did something to drive the loser crazy. And they call women emotional!
"I know your forensics people will narrow down the time, but it seems like it must have happened either during Tim and Bess's fight or shortly after. At least that's what I thought until I looked at the computer. See the mouse pad? It's on the right, which makes sense since Gretchen was right-handed. But the mouse itself is on the left."
Her father saw this and scratched his head. "She wasn't the last person to use the computer? That means the off-line mail she was writing--"
"Right. Someone else wrote it, at least the last part. The question, of course, is why. Why would the killer take the time to rewrite Gretchen's mail?
"It doesn't matter," Harry said excitedly. "Our killer's left-handed. All we have to do is find the left-handed suspect. I hope there's not more than one."
"We don't even need to check. It's clear to me right now who did it." So, who strangled Gretchen White? And what led Amy to her conclusion?