Forensic linguistics is at the cutting edge of the undercover policing of child sexual abuse on the open internet and dark web, and language and identity is a fundamental part of this. The authors have drawn on their extensive experience in training undercover officers to develop innovative methods in identifying the creation and performance of online personas, crucial in detecting identity disguise online. This groundbreaking book demonstrates these methods through case studies, whilst also exploring the link between language and identity. By bringing together previously opposed positions in forensic authorship analysis, the book develops a novel theory of linguistic identity, which will resonate not just in forensic authorship research but in sociolinguistics more widely. This unique forensic linguistic project has real-life impact in assisting the police in their investigation of online abusers, and has impact for students and researchers of linguistics, through its contribution to the research of linguistic identities.

'Language and Online Identities is a very readable book crammed with newly researched, important and often disturbing material of a kind not publicly available before and all well illustrated with fascinating examples.' Malcolm Coulthard, Federal University of Santa Catarina, Brazil
'The authors should be commended for their incredibly important work in this area. The field of forensic linguistics is better for it, not only for how it has already helped law enforcement, but also for the ways in which we can use the information presented here to help protect the vulnerable in the future in an ever-increasingly online world.' Karen E. Lillie, State University of New York, Fredonia

Tim Grant is the UK's only Professor of Forensic Linguistics, at Aston University, providing academic research and expert investigative assistance to UK and overseas police forces as well as providing evidence for both prosecution and defence and in civil cases. He is a former President of the International Association of Forensic Linguists. Nicci MacLeod is a Lecturer in English Language and Linguistics at Northumbria University. She has published in a number of peer-reviewed journals and edited collections, and provided expert reports to several police forces as well as to solicitors and private clients in criminal and civil cases.