Child sexual exploitation and abuse (CSEA) needs more attention from a crime prevention perspective. This is the first in a two-part series about the PrevBOT concept, which is an automated tool supporting the police in preventing CSEA in online chat rooms. Part I presents the concept, its theoretical framework, and the technology. Equipped with technology for Authorship Analysis, the tool can identify problematic digital spaces unsafe for children. Given the advancements in machine learning algorithms, PrevBOT may provide predictions concerning age and gender behind online aliases engaged in sexualized speech with children and assist the police in identifying former CSEA offenders who resume the criminal activity online. Part II provides a legal analysis of issues relating to data protection, privacy, and fair trial.