This paper analyses children's crime novels and their characteristics, with special emphasis on the formation of children's characters who play the role of investigators in the novel. This genre in children's literature draws special attention towards both children and adult readers alike because it accurately portrays real-life relationships amongst children and between children and adults. Within the novel, the social and existential opportunities of the characters and their families are of no less importance. The child's character is constructed to realistically portray the nature of the child, their thoughts, feelings, turmoil, intelligence, imagination, resourcefulness, attitude towards elders, and their attitude towards their family. This paper provides an overview of Croatian authors who write children's crime novels. In order, they are: Ivan Kušan (Uzbuna na Zelenom Vrhu, Koko u Parizu), Pavao Pavličić (Trojica u Trnju, Zeleni tigar), Zlatko Krilić (Zagonetno pismo), Jadranko Bitenc (Lana – godina mačke), Anto Gardaš (Duh u močvari, Miron u škripcu), Hrvoje Kovačević (Tajna ribljeg oka) and Ivona Šajatović (Tajna ogrlice sa sedam rubina). A very important feature of a children's crime novel is the formation of children's families. One can say that a children's family, is the general structural element of a children's novel. The authors place children in unknown and exciting situations, in which they monitor their feedback to format their characters. Everything is subordinate to them, and like so, the extent to which they will seek adult help. Within some parts, it is visible how children attempt to solve situations without adult support and are therefore put on the sideline until they decide that they need help (Trojica u Trnju). In the meantime, other children and adults mutually participate in solving situations (Zagonetno pismo).