Old Mr. Tidy was found dead in his study by Mr. Fiend.
Mr. Fiend recounted his dismal discovery to the police.
"I was walking by Mr. Tidy's house when I thought I would just pop in for a visit. I noticed his study light was on and I decided to peek in from the outside to see if he was in there. There was frost on the window, so I had to wipe it away to see inside.
That is when I saw his body. So I kicked in the front door to confirm my suspicions of foul play. I called the police immediately afterward."
The officer immediately arrested Mr. Fiend for the murder of Mr. Tidy.
How did he know Mr. Fiend was lying..?