The following article contains an answer for the question: Who is the innocent little mouse? , can you please find it? 

Tom is sleeping near the fireplace, and Jerry carefully sneaks past him. He goes up onto the dinner table and tries to reach for the food, but Tom attempts to slice him with a knife and he retreats, running up the staircase. Tom pulls the carpet off the staircase to catch Jerry, but also pulls down a large upright piano. While Jerry gets out of the piano's path, the piano crushes Tom to death. Tom's spirit ascends to the "Heavenly Express", a steam train that sends dead cats to Heaven.
Several cats are waiting to enter and the gatekeeper goes though their lives. The cats include Butch, who has lost a fight with a bulldog. Frankie, who was struck with a flat iron while singing on a backyard fence. Aloysius, who was run over and flattened by a steamroller. Even Fluff, Muff and Puff, a trio of kittens who were drowned after being thrown into a river. The gatekeeper allows them all through, as their deaths were untimely. However, he catches Tom trying to sneak past him to board the train and tells him to stand in line. The gatekeeper looks through his personal records and is disappointed by what he sees in it. Having learned that the main cause of Tom's death has been attributed to him persecuting "an innocent little mouse" all of his life and not from an accidental crushing of the piano, the gatekeeper refuses has entry to him for that action alone. He apologizes for this inconvenience, but the gatekeeper gives him a chance for a reprieve; should Tom have Jerry sign a certificate of forgiveness, he will be able to board the "Heavenly Express", which leaves in one hour. If he fails, Tom will be banished to hell where the hellhound devil awaits.

Jerry