FBI investigations of a heinous online child predator network have expanded to target more than 450 people, the bureau said on Tuesday. Officials continue to crack down on groups going by names such as “764” that lure children into violent online communities and induce them toward self-harm or sexual acts, FBI Dallas Special Agent in Charge Joe Rothrock said in a statement warning parents and schoolteachers. Authorities have traced similar groups’ beginnings to at least 2019, announcing more than 350 subjects of investigations by late last year. FBI Dallas is sharing information with parents, guardians, and teachers about violent online...