Case Closed Episode 566 SUB at Gogoanime

Synopsis: A young widow named Shigeko Ishikawa is being stalked by an unknown man, who has hung around her house and tried to push her down a public stair. Kogoro is walking around the streets and sees the last incident, and Shigeko hires him to find said stalker before they actually hurt her and her two-year-old child, Santa. Since Ran is training with the karate team, Conan is forced to watch over Santa. Source (DCW Wiki)