This article discusses the norms of studying the written speech of adolescent girls from a graphological point of view. Networks of graphology and its importance in linguistic expertise, the role of letter changes in determining the author of the text, the results of research to determine the specific features of the letter forms of adolescent girls written speech and natural and altered (spontaneous) writing the differences between the speeches are highlighted. The study of written speech focuses on a number of linguistic features inherent in speech, including spelling, phonetics, lexical-semantic, stylistic and grammatical differences, and individuality. Some of the topographic changes that occur in the written speech of adolescent girls, the author's psychological, individual, as well as linguistic views on graphological criminology are described through letter forms.