Frozen Windows

Riddle: Once on a winter day, John found his friend dead in his own house. John called the police and said that he was just passing by Jack's house and decided to come in. He'd been knocking and ringing the bell for a long time, but all was silent. However, he could see the light in the room through a frozen window. He breathed on the iced window glass and saw Jack on the floor. The police arrested John as the main suspect. Why?

Answer: John wouldn’t be able to unfreeze the window glass because it’s usually icy on the inside.

Source: https://www.riddles.com/index.php/6611

Once on a winter day, John found his friend dead in his own house. John called the police and said that he was just passing by Jack's house and decided to come in. He'd been knocking and ringing the bell for a long time, but all was silent. However, he could see the light in the room through a frozen window. He breathed on the iced window glass and saw Jack on the floor. The police arrested John as the main suspect. Why? — Frozen windows by Regina Mills v1.

Riddle: Once on a winter day, John found his friend dead in his own house. John called the police and said that he was just passing by Jack's house and decided to come in. He'd been knocking and ringing the bell for a long time, but all was silent. However, he could see the light in the room through a frozen window. He breathed on the iced window glass and saw Jack on the floor. The police arrested John as the main suspect. Why? Answer: John wouldn’t be able to unfreeze the window glass because it’s usually icy on the inside. — by Regina Mills v2.